Auto-Fill fills your empty days quickly to get your calendar started. It's only available on the Android app; on iOS, use Quick Fill instead (see How to Use Quick Fill).
Scroll to days with a video camera icon on them.
Tap the Auto-Fill button at the top right of the calendar screen.
Tap Keep to save the preview or Discard to cancel it.
You'll see the snippets before you decide whether to keep them, and you can cancel at any time.