Take the money before the groom
Tap Take payment on a booking that hasn't happened yet. It gets paid without being finished — it still sits on your day.
Open a booking that hasn't happened yet and tap Take payment. You can do this the moment the booking exists.
Paying does not finish the job. The booking stays on your day and you still Start it as normal. The only thing that changes is that the app stops asking you for money: it shows a Paid badge, and the button that said Checkout now says Finish.
That's on purpose. Paid and done are two different facts, and plenty of clients pay for next fortnight's groom today.
If the price changes on the day
Add the extras at Checkout as usual. The app works out what's left and offers to collect only the difference — you won't charge the whole booking twice. If it comes to less than they already paid, it tells you how much credit they're owed so you can sort it out with them.
Cancelling a booking that's already been paid does not refund it. The app warns you before you cancel and tells you how much was collected — it's up to you to settle up with the client.
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