Appointments are made via the calendar, and only after payment has been made. (See the "Pay" tab at the top of this page.)
Special Note #1: The 40-minute time slot has some flexibility where possible. If no one has booked the slot after yours, and I have no other pressing engagements after your session, then I can be more flexible with our time together - and at no extra cost to you (but certainly within reason).
Special Note #2: The booking page may reflect "30-minute" sessions, but the session is 40 minutes (and flexible - Read above and below for details). There was no way for me to denote the 40-minute time-slot on the scheduling page.
In fact, after your session allotment is done, I have no intention of cutting-you-off at your "deadline" necessarily. But if someone has booked the slot directly after yours, or if I have other things I need to do, then at the end of your allotted time, we will need to wrap-things-up so that I can get ready for the next hour. Nonetheless, it is likely that you will get more than your allotted time at no extra cost to you - but I cannot promise this.