The steps given below allow you to add a payment in advance while scheduling an appointment:
Go to "Calendar".
Click on "New Booking"
3. Generate the appointment for the client while adding the services, staff, date and time.
4. If customers pay you in advance for the the booking, they may not availing it. Then, you can simply choose your payment method.
When the client visits, the appointment will be scheduled with a paid status; however, change the booking status to complete and save.