Reporting part-time earnings while on benefits

I picked up part-time shifts as an administrative assistant and I am confused about how to report them. There are 3 people counting on me, so I am trying to be careful. 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.