I want to work at publix? i haven't had a job yet?

ok, so i'm 15 and i'm starting to look for a job, because i'm going into sophomore year in august and i think i should start making some more money. i want to work at Publix as maybe a bagger, because i've been thinking about this for a while. Would it be better for me to apply right before school starts, or while it's still summer? i'll be gone for about a week or two, and any other tips or advice would be appreciated. thanks