How do I set up a closure for my holiday?

Add a dated closure with a start and an end. It switches on and off by itself, in your store's timezone. You don't need to log in on the day.

Steps

Open the app and go to Closures.
Click Add closure.
Under Name, type a name, for example "Christmas 2026". Only you see this.
Leave Type on Dated: a holiday with start and end.
Set Closes on and At, for example 22 December, 16:00.
Set Reopens on and At, for example 3 January, 09:00. This is when you reopen.
Under Orders while closed, choose Keep selling and show when orders will ship or Block checkout (shoppers can still browse). See Should I keep selling or block checkout?
Optional: set Dispatch from (optional). Leave it empty to dispatch on the reopen day. See What's the difference between the dispatch date and the reopen date?
Under Where to show it, tick the places you want: Store banner or popup, Product page notice, Cart notice, Dispatch date in checkout shipping names (keep selling) and Thank-you and order status note (keep selling). All are ticked to start with.
Under Text for this closure, leave a field empty to use the text shown in grey, or type your own.
Check the Preview on the right, then click Save.

Times use your store's timezone, shown under the dates. You can change it in Shopify admin under Settings → General. Times go in 15-minute steps. Clock changes are handled: a 09:00 reopen stays 09:00.
You can have as many closures as you like. On Closures, each one shows as Scheduled, Active, Ended or Paused.
To stop a closure without deleting it, open it and tick Paused.
If two closures overlap, then for the overlapping time Block checkout wins over Keep selling. If both have the same mode, the one that ends later wins. The editor warns you when a closure overlaps another.
Next year, click Duplicate next to an ended dated closure on Closures. The copy is moved to the same dates next year and named "(copy)". Check the dates, then save.
In messages, {dispatch_date} and {reopen_date} are swapped for the real dates.