How do you report hours that vary week to week? (update)

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

Keep everything in writing and save the confirmation numbers. It saved me later.

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.