You can set a default appointment time in your account so that appointments will be booked for the time you set. You can always change individual appointment times or set appointment times with appointment profiles.
To set a default appointment time:
1. Go to Account > Provider Settings and click on the General tab.
2. Select the number of minutes with the (
3. Scroll down and select 
With this set, all new appointments created will automatically be set to the time that you entered.