Wage reporting when hours change weekly after 14 years as an event coordinator

I work some days through a staffing agency while still certifying. I am in Tulsa, in case local advice matters. 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?

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.