as someone who worked overnight grocery for twenty years, my main advice would be to keep organized. have a separate runner for trash with a plastic bag tied to the end for your plastic trash and a milk crate for damages (and the occasional stool if you need it though i'm sure that's frowned on for safety reasons)

don't get frustrated. one of the hardest things at first is finding the product on the shelf. it takes time. if they put you on breakdown, it's going to take time to learn which runner is which. your crew chief (or team leader or whatever they call them now) will understand and will simply looking at effort and reliability for the first few weeks and months

it's a hard job, a demanding job, but it can be a lot of fun