How do you report hours that vary week to week? after 3 years as a school bus driver

I picked up part-time shifts as a school bus driver and I am confused about how to report them. It has been weighing on me all week. Pay posts on a different day from when I work. Did anyone get an overpayment notice from a mistake?

I estimated and then checked my pay stub. When there was a small difference I wrote to the agency to correct it.