How do you report hours that vary week to week? - first time posting

I picked up part-time shifts as an IT help-desk technician and I am confused about how to report them. It has been weighing on me all week. Sometimes my paycheck is late by a week. Do you report when you earned it or when you were paid?

Thanks for writing this out. I went through something close to it last year, and it settled down once I kept a simple log of every call and form.