How do you report hours that vary week to week?, electrician's helper here

My hours change every week at my new part-time job and I am afraid of reporting wrongly. I worked as an electrician's helper before this. Sometimes my paycheck is late by a week. Who can I ask without risking my claim?

Thanks for writing this out. I went through something close to it 12 months ago, and it settled down once I kept a simple log of every call and form.