How do you report hours that vary week to week?

I work some days through a staffing agency while still certifying. I have read a lot of threads here and could not find my exact situation. Pay posts on a different day from when I work. Who can I ask without risking my claim?

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

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