If you have school let them know or a planned family vacation you had planned months beforehand they are fine with that just make sure you are upfront. Be available Friday nights from 5pm to close (if you put 5-10pm you are useless to them) Saturday open to close (you won't be scheduled all day) and Sunday open to at least 5 but later is recommended (and if your religious out 3pm-close or whenever your church gets out). And give them at least one weekday. Remember try to give them something to work with they have STACKS of dusty applications in the office. And you can change your availability as time goes on. And don't worry if they wear you down with hours in summer business dies during school time so you'll be working 2-3 days max.