Reporting part-time earnings while on benefits - 14 weeks in

I picked up part-time shifts as a software tester and I am confused about how to report them. There are 5 people counting on me, so I am trying to be careful. Pay posts on a different day from when I work. Do you report when you earned it or when you were paid?

The claimant handbook has worked examples for part-time pay. Mine was clearer than the phone line.