You can nominate a buffer time between appointments in your online booking preferences.
To add a buffer time:
Click Personal > Locations.
In the Hours, Profile and Book Preferences section, click the Expand (+) icon next to the name of the practitioner whose settings you are changing.
Click the Edit (pencil) icon next to "Online Bookings and Profile Preferences".
In the "Buffer time" field, enter the number of minutes you want added to each appointment as a buffer.
RESULT: Your Online Bookings time slots will adjust so that appointments cannot be made within the specified buffer time. Note that buffer time applies to the end of the day as well; for example, if your day ends at 6:00 PM and you have a 10-minute buffer time, a patient would not be able to make a 30-minute appointment at 5:30 PM (you would need to set your hours to end at 6:10 PM to allow this).