Reporting part-time earnings while on benefits - any advice?

My hours change every week at my new part-time job and I am afraid of reporting wrongly. I would rather hear the honest version than the polite one. Pay posts on a different day from when I work. Did anyone get an overpayment notice from a mistake?

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