How do you report hours that vary week to week? - 7 weeks in

I picked up part-time shifts as a copywriter and I am confused about how to report them. Any experience at all would help. The form asks for gross earnings, which I do not see until later. Who can I ask without risking my claim?

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

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