How do you report hours that vary week to week? - 22 weeks in

I picked up part-time shifts as a call-centre agent and I am confused about how to report them. I worked as a call-centre agent before this. Pay posts on a different day from when I work. 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.