How do you report hours that vary week to week? after 4 years as a logistics coordinator

My hours change every week at my new part-time job and I am afraid of reporting wrongly. I have been trying to stay organised about it. Sometimes my paycheck is late by a week. 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.