How do you report hours that vary week to week? after 11 years as a janitorial supervisor

My hours change every week at my new part-time job and I am afraid of reporting wrongly. I have read a lot of threads here and could not find my exact situation. The form asks for gross earnings, which I do not see until later. Did anyone get an overpayment notice from a mistake?

Thanks for writing this out. I went through something close to it 2 months ago, and it settled down once I kept a simple log of every call and form.

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