Wage reporting when hours change weekly after 13 years as an accountant

I picked up part-time shifts as an accountant and I am confused about how to report them. I would rather hear the honest version than the polite one. 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 14 months ago, and it settled down once I kept a simple log of every call and form.