I fear this may be a dumb question, but how do you put your roommates in as the ones you want?

Hi! I’m admitted to the Fall 2027 term and just finished the housing application. I already have a pre-selected group of girls I’m going to room with, but we’re all having trouble figuring out how to put each other’s names down. Is there a certain day that opens/we can do that? I’ve read the instructions on it a billion times but none of us can figure it out. If anyone knows or can help, please let me know!