What is the best time to run scheduled jobs on GitHub Actions?

When running a scheduled job at 04:20 UTC I experience a delay of 40 Minutes until it is actually run. In my use case that is not critical, but I want to avoid busy times. But what are those busy times? The documentation states: “High load times include the start of every hour.”, but gives no further details.

So I ran two jobs every two hours, one on the even hours, the other one on the odd hours. These are my results:

My conclusions:

  • Delays up to 20 minutes are normal
  • The hours 0 - 4 are very busy, the hours 0 and 1 are extremely busy. Avoid these hours.
  • The hours 12, 13 and 16 are quite busy as well.
  • During the week the variations are quite small, it doesn’t really matter at what weekday the job is running.

Any comments?