Resignation letters/two week notice?

I've been working at walgreens for only a week part time and i got a full time job offer from valvoline. I want to take this job offer cause its better hours that suit my life. Im putting in a resignation letter for walgreen but does it have to be a two week notice since im working only leftover hours and im not actually on the schedule until June 4th. Valvoline wants me to start right away. So what should i give walgreens if i decide to ever come back in the future??