Wage reporting when hours change weekly - what worked for you?

I picked up part-time shifts as a procurement assistant and I am confused about how to report them. I have been trying to stay organised about it. 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.