Reporting part-time earnings while on benefits

I picked up part-time shifts as a social media manager 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. Did anyone get an overpayment notice from a mistake?

Thanks for writing this out. I went through something close to it 3 months ago, and it settled down once I kept a simple log of every call and form.