when do i choose my university?

Answer 1

you should have a good idea for possibilities by the end of your junior year.

Answer 2

First you visit colleges or thnk about which colleges you want to apply to. Then you make a final decision on where your going to apply, once you've applied and sent everything off you wait (first semester senior year). Once your admittance letters come in, you have to start choosing from where you've been accepted (March-April of your senior year).