Scheduled an hour too early to work

I got hired by a retail store yesterday and am being trained today. My trainer doesn’t come in until 9 so I told my manager and she said she’d change my hours to start at 9. She never changed it and I am scheduled at 8 and she also isn’t coming today. Am I going to get in trouble for coming at 8 and doing nothing (I bake and wasn’t showed where anything in is)