TimeRex allows you to set aside "before/after" time before or after the meeting time.
This can be set for all plans.
Required time: 60 minutes
Reserved time before and after: 30 minutes
If you set up like this, the total time of 120 minutes (30 minutes to go, 60 minutes to require, and 30 minutes to return) will be entered in Google Calendar.
Only those times when the total time can be secured, including the time before and after, will be displayed as candidate dates in the schedule adjustment calendar.
The default values are 0, 30, 45, and 60 minutes.
Custom settings allow the user to freely set the time secured before and after in 1-minute increments, up to 180 minutes.