Open Question: urgent help relating to dental cavities?

So tomorrow im going to get seperators for bracers, and the day after that im getting the braces. Yesterday i went to the dentist to get a clean and he said that i have two cavities. My question is, can i get fillings for the cavities while i have seperators on? I dont have any time to get the fillings before i get the seperators. and im not sure where the cavities are. thanks!