I was 3 years into a degree when I applied for ATC..... Had no prior knowledge of anything to do with aviation to be honest...... But I was honest about it and the interviewers seemed to be more interested in the fact I had loads of summer jobs on the go to pay for college .....then knowledge of aviation.
The 3 years study didn't come in handy at all but didn't do me any harm either . I'd just apply first and then if you don't get in go and study something else. Good luck whatever you decide