How do you report hours that vary week to week? - 9 months and counting

I picked up part-time shifts as a web developer and I am confused about how to report them. I worked as a web developer before this. Sometimes my paycheck is late by a week.

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

I estimated and then checked my pay stub. When there was a small difference I wrote to the agency to correct it.