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. The form asks for gross earnings, which I do not see until later. Who can I ask without risking my claim?

In my state the question was about the week I worked, not the week I was paid. Read the wording on your form carefully, or ask the claims line.