I'm sure you'll do great. The busy retail environment can be intimidating at first, but you learn to embrace it. When I was hired as a cashier 3 years ago, I had five "training shifts" over two weeks (albeit with limited availability because of school), but the cashiering tutorial was in the first shift and the rest of the shifts were essentially for practice and completing my learning plan. When I trained in hardlines, I had a few days of training shifts.