How do you report hours that vary week to week? (Richmond)

My hours change every week at my new part-time job and I am afraid of reporting wrongly. Any experience at all would help. The form asks for gross earnings, which I do not see until later. Do you report when you earned it or when you were paid?

Keep everything in writing and save the confirmation numbers. It made the follow-up calls so much easier.

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