You can either set a before event buffer time, an after event buffer time, or both. Here’s how to do that:
1

Select your event type where you wish to add the buffer time
2

To add a buffer time, click on the Limits tab
3

Then, click on the before event, or after event select box to view the buffer time options in minutes and select the buffer time of your choice
4

Click on Update to save your changes. Your event type should now consider the newly added buffer time