Most of what goes wrong over Black Friday was changed in the fortnight before it. A new popup app, a last-minute theme tweak, a discount that stacks with free shipping in a way nobody tested. This is the list we work through with clients so the week itself is boring.
The dates
| Milestone | Date (2026) | What it means |
|---|---|---|
| Prices and compare-at prices set | by 12 November | Check each promoted variant against its lowest price since 28 October |
| Theme and app freeze | from 17 November | Bug fixes only, tested in a duplicate theme |
| Black Friday | 27 November | Promotion starts; watch stock, checkout and site speed |
| Cyber Monday | 30 November | Last push; reset prices and compare-at prices afterwards |
1. Freeze the store, then audit it
Pick a freeze date and stick to it. After that date nothing new is installed and nothing structural changes in the live theme. Before the freeze, go through installed apps and the theme code:
- Remove apps you no longer use and check that their scripts left the theme too. Uninstalled apps often leave snippets behind.
- List every third-party script that loads on product and collection pages. Each one competes with your hero image for the first second.
- Make a duplicate of the live theme as a rollback point.
Why scripts matter more than anything else in this week is covered in third-party scripts and Shopify performance.
2. Test speed with the campaign live
Teams measure the homepage in October and launch in November with a countdown bar, a full-screen popup and a video hero. Measure again with everything switched on, on a mid-range Android phone over mobile data. The largest image on the page decides how fast it feels; preload it, never lazy-load it, and serve it at the size it displays. Our full method is in the Core Web Vitals playbook.
3. Discounts: decide what stacks
Shopify lets product, order and shipping discounts combine with each other or not, set per discount. Write down the intended combinations, then test each with a real checkout:
- Automatic sitewide discount plus a newsletter code: should they stack?
- Percentage code plus free shipping threshold: does the threshold use the pre- or post-discount subtotal?
- Bundles and buy-X-get-Y: do they interact with the sitewide discount as intended?
- B2B or wholesale customers: are they excluded from consumer promotions?
4. Stock, fulfilment and delivery promises
- Turn off continue selling when out of stock on promoted products.
- Confirm cut-off times and capacity with your carriers. If delivery slows that week, update the delivery estimate on product pages rather than leaving the usual one.
- Check that order confirmation and shipping emails still read correctly with discounts applied.
5. Checkout and payments
Place a real order with every payment method you offer, including wallets and buy now, pay later. Refund them afterwards. If you run checkout extensions or Shopify Functions for discounts or shipping rules, test those paths too; since Shopify Scripts stopped on 30 June 2026 that logic lives in Functions, and a forgotten edge case shows up first under volume.
6. Pricing rules for UK and EU shoppers
In the EU, anyone announcing a price reduction to consumers must show the lowest price applied in the 30 days before the reduction. In Aldi Süd (C-330/23, 26 September 2024) the Court of Justice added that the advertised discount, including the percentage, must be calculated from that lowest price. Shopify does not track it for you: the compare-at price field shows whatever you enter, and many themes calculate the percentage badge from it. Set it to the 30-day low, not the highest price of the year.
In the UK there is no fixed 30-day formula. A was price must still be genuine: comparing with a price the product was never really sold at is misleading, and since the DMCC Act's consumer provisions took effect on 6 April 2025 the CMA can enforce consumer law directly, including fines. Countdown timers that reset and stock warnings that do not reflect real stock fall in the same category. More on UK rules in UK online selling rules for Shopify stores.
7. After Cyber Monday
Reset prices and compare-at prices on a fixed date, export your discount usage and refund data, and write down what broke. That note is the start of next year's checklist. If you want a second pair of eyes before the freeze, we run this review as part of a Shopify retainer or as a one-off speed audit.