Buffer time
From SimplyBook.me
Go to Manage // Services // Pen icon and:
1. Change Service duration to Actual duration + buffer time (Example: actual duration 45 min, buffer time 15 min, you set up duration to 1 hour).
2. Press Hide duration link.
3. Put actual duration to Service name, so the name of the service could be for example “Counselling - 30 minutes”.