The buffer on a calendar will only appear after a booking has been made. Check out Setting Your Availability for more details on how to add a buffer to your Calendar.
Take this example:
60 minute interview
60 minute buffer after event
Interviews start every 60 minutes
What the calendar looks like initially:
After a booking has been made at 10 AM, this is what the calendar looks like:
The next available appointment is at 12 PM (10 AM to 11 AM appointment, 11 AM to 12 PM buffer).