It's different depending on the Banfield you're applying to. In January or February of last year, I applied on the website, using my vet school email (to verify I was a student there) and they contacted me after about 2 months. I basically had the job after applying for it, and I didn't really have to interview (no one else had apparently applied for it... red flag :/). Then when I was home in MArch during Mardi Gras break, I went to the clinic and toured it and met the doctors and some of the staff. For other people at my school, they held interviews in March (I think, I don't remember the time line because I didn't participate in the interviews there). After that it was a bunch of corporate paperwork.
Good luck.