How to Share Your Peak Forecast With Your 3PL (and What They Actually Need From You)

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Imagine ringing a restaurant and saying, "We'll be coming for dinner. It'll probably be busy."

They'd want to know more. How many of you? What time? Are you all eating at once, or in waves? Does anyone have allergies? Without those details, the restaurant can only guess, and so it either over-prepares and wastes food, or under-prepares and runs out of tables.

That's what many founders tell their logistics partner about Black Friday. "It'll be a big one" feels like useful information when you're the one carrying the stress. To your 3PL, it's the equivalent of "it'll probably be busy": true, and almost impossible to plan around.

The good news is that a useful forecast isn't complicated. It doesn't need to be accurate to the unit, and it doesn't need a data science degree. It needs to give your logistics partner enough specifics to book the right people, the right space and the right carrier capacity. This guide covers what they need, how to build it, and includes prompts you can paste into an AI assistant to work it out step by step.

Why "It'll Be Busy" Isn't a Forecast

Your 3PL can see your normal order patterns. What they can't see is what's happening on your side: when your emails go out, when your ads scale, which product you're about to push, or whether a creator is posting on Thursday.

From their side, a good forecast lets them plan for four things:

A forecast that covers those four areas lets them plan properly. One that doesn't leaves them guessing, and when a warehouse is guessing at peak, the person who usually pays is you.

If you're building in public, there's another reason to get this right. Your audience can see your sale coming, which means your promises are already out there. A forecast turns those public promises into something your operation can actually deliver.

Must-Do Action:

Replace "it'll be busy" with numbers and dates, even rough ones. A range with a clear explanation is far more useful than silence.

What Your 3PL Actually Needs From You

Here's the information that helps most, in rough order of importance.

What they need

Why it matters

Example

Promotion dates

Sets the shape of the peak: when volume starts, builds and ends

Early access Wed 25 Nov, main sale Fri 27 Nov to Mon 30 Nov

Daily order volumes

Drives labour and carrier planning

Normal: 150/day. Base: 300/day. Stretch: 450/day

SKU-level volumes

Drives stock placement, picking and replenishment

Top 5 products make up about 70% of units

Marketing activity

Shows when spikes are likely, not just when the sale starts

Email at 8am Friday, Meta budget doubles from Thursday

Launches and new products

New SKUs need setting up and slotting before they arrive

New gift set launching 25 Nov, 500 units arriving 16 Nov

Inbound schedule

Lets them plan receiving, which can be a bottleneck at peak

3 pallets on 2 Nov, 2 more on 9 Nov

Order profile

Bundles, gift notes and special packing take longer

30% of orders will be multi-item gift sets with a card

Subscription rebill dates

Rebills add volume on top of the sale

1,200 renewals on 25 Nov

Service promises

Sets the deadlines they need to work to

Orders before 2pm ship the same day. Last Christmas order date 15 Dec

Contacts and escalation

Gets problems solved quickly when it's busy

Who to call, who decides, who's on call at weekends

You don't need every row on day one. Start with dates, daily volumes and your top products, then fill in the rest.

Worth-Trying Tactics:

Put everything on one page and send it as a single document. It's easier for your account manager to share with the warehouse team than a trail of separate emails.

How to Build Your Forecast (With Prompts)

If you've never built a peak forecast before, it can be hard to know where to start. The prompts below are written so you can paste them into an AI assistant such as Claude or ChatGPT, fill in the square brackets with your own numbers, and work through the process step by step.

A few ground rules before you start:

Step 1: Build a Daily Order Forecast

Start with the big picture: how many orders per day, across the whole peak window.

I run a D2C brand selling [product type]. On a normal day we get about [number] orders. Our biggest previous promotion was [describe it, e.g. "a 20% off weekend in March"] and it increased daily orders by about [x times / x%] at its peak and lasted [number] days. We have no / some history of Black Friday.

This year, our sale runs from [start date] to [end date]. Early access for subscribers starts on [date]. Our main marketing activity is [e.g. "a big email on the Friday, Meta ad budget doubling from Thursday, two creator posts"]. Our monthly ad spend is normally [amount], and for the sale it will be [amount].

Please create a day-by-day order forecast from [date] to [date], with three scenarios: a base case, a stretch case and a wildcard case where something goes unexpectedly well. Show your assumptions for each scenario clearly, and tell me which numbers you are least sure about.

If you have no history at all, add this to the prompt:

I have no previous peak data. Please suggest a cautious range based on my ad spend, my normal conversion rate of [x%] and my average order value of £[amount], and explain how you got there so I can check it.

Step 2: Break It Down by Product

Your 3PL needs to know which products are going to move, so they can put stock in the right place and plan replenishment.

Here are my top products and their share of units sold in a normal month: [Product A: x%, Product B: x%, Product C: x%, etc.]. During the sale, I'm promoting [products] most heavily, and I'm launching [new product, if any] on [date].

Using the daily order forecast above, please estimate units per day for each of my top [5–10] products across the base and stretch cases. Flag any product where demand could change a lot compared with its normal share, and tell me why.

Step 3: Pressure-Test It

This is the step most founders skip, and it's the most useful. Ask the AI to find the holes in your plan.

Act as a sceptical operations manager at a third-party warehouse. Here is my peak forecast: [paste your forecast]. Here is what I plan to tell you: [paste your dates, marketing plan, inbound schedule].

What's missing? What would you want to know before agreeing to this? Which assumptions look too optimistic? What questions would you ask me, and what could go wrong on peak day that I haven't considered?

Step 4: Turn It Into a One-Page Brief

Now put it into a format your 3PL can use.

Using the information below, write a one-page peak briefing for my logistics partner. Include: promotion dates, daily order volumes (base and stretch), top product volumes, marketing activity timeline, inbound deliveries, order profile (bundles, gift notes, special packing), subscription rebill dates, service promises and cut-off dates, and key contacts.

Keep it clear and factual, with a short summary at the top. Use tables where they help. Here is my information: [paste everything].

Step 5: Plan How You'll Update It

A forecast isn't something you send once and forget. It needs updating as things change.

My peak forecast says we expect [number] orders on [date]. Create a simple daily tracking sheet I can use during the sale, with columns for forecast, actual orders, difference, and a note.

Also suggest three trigger points, for example "if orders are more than 30% above forecast by midday, I will tell my 3PL and consider placing a reserve stock order". Make them specific and easy to act on.

Must-Do Action:

Work through at least Prompts 1, 3 and 4. The forecast, the pressure test and the briefing are what make the difference.

What to Do If You Fulfil Yourself

If you pack your own orders, you're your own 3PL, so the same forecast applies to you. Use it to plan:

Prompt 3 is particularly useful here. Ask the AI to act as an operations manager reviewing your plan, and see what it finds.

When and How to Send It

Send your first forecast as early as you can. Check your 3PL's own deadline for peak forecasts and inbound bookings, and don't wait for them to ask. The earlier your logistics partner knows, the more options they have.

After that:

Worth-Trying Tactics:

Agree in advance how you'll communicate during peak: a shared channel, a daily call, or a morning message. When it's busy, a simple routine beats an ad hoc scramble.

What a Good Response Looks Like

When you send your forecast, pay attention to what comes back.

Green flags:

Red flags:

If you get the red-flag version, it's worth pushing for clearer answers. Our guide to stress-testing your fulfilment [link] covers what to look for.

Make It Easy for Them to Say Yes

A good forecast isn't about being right. It's about being clear. It gives your logistics partner the information they need to do their job, and it shows you've thought about what peak will demand of both of you.

You'll almost certainly be wrong about some of the numbers. That's fine, as long as you've said what you expect, why you expect it, and what you'll do if reality turns out differently. That conversation, held in October, is what keeps November calm.