I want to use this plugin for my tutoring company. Customers pay per 15 minute interval. However, it is very common in tutoring that a session goes longer or shorter than planned. In my experience, the easiest and most common way to deal with this is to simply not charge the customer until after the session is complete. So, I would like BookingPress to allow the customer to book first--perhaps have them enter their payment info to confirm the appointment--then allow the employee to finalize the length of the appointment and subsequently charge their payment method and write up the invoice.
For example, say a client books a 1 hour SAT prep session at $60/hr, but the session ends up lasting only 30min. Then, the tutor should be able to charge the client afterwards for 0.5 hours or $30. This is much easier, faster, cheaper, and logistically simpler than having to refund them afterward. Of course, then the tutor's page would have to reflect the actual time spent tutoring so that I can pay them correctly.