How do you report hours that vary week to week? - 11 months and counting

My hours change every week at my new part-time job and I am afraid of reporting wrongly. There are 6 people counting on me, so I am trying to be careful. The form asks for gross earnings, which I do not see until later.

Report honestly and keep your stubs. An honest small error is much easier to fix than a missing report.

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