What do I do when a client is running late and the next booking is right after her?
Build the margin into the service itself: each one can have a buffer after the treatment that blocks your time, so the next client can't be booked back to back. Reminders 24 and 2 hours before go out automatically: email on any plan, SMS on Pro. Write your lateness rules in the service description — the client sees them on the booking page before she picks a time. If the day still slips, move the next booking in the calendar: the client gets a notification with the new time.
