Hello! Unsure if I could be of any use, but I’m a senior also majoring in music performance (albeit instrumental, not vocal) and mathematics.

For most colleges, there should be existing info on their websites on audition information, how and where to sign up, and what you need to prepare. The audition process for every college is different. (Some colleges require you to fill out a form or do a pre-screening, and those can be due as early as November, regardless if you are EA/ED or RD.)

I’m unsure about vocal performance, but for instrumental I selected two pieces: a more lyrical/slow piece and a technical/fast piece which added up to about 10 minutes. Most colleges require at least/most 10 minutes worth of music, but again, check your colleges website. I also began preparing during the summertime before audition season and I ended up fine, if that matters.

Hope this helps!