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

I work some days through a staffing agency while still certifying. I am in Seattle, in case local advice matters. Pay posts on a different day from when I work. Did anyone get an overpayment notice from a mistake?

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.