The process starts way earlier than the interviews. Deloitte was on campus starting in mid-September conducting on-campus info sessions, some more formal than others. I believe that interactions early on greatly factor into their decision of who to bring in for interviews. The on-campus interview process was two days long. The first round was one 30 minute case and one 30 minute behavior (in no particular order). If successful, Deloitte will call you later that night confirming your second round interview (it was the next day for me). The second round consists of a longer, more involved case interview (~1 hour). I also met with a partner for a second 30 minute behavioral interview, since I didn't interview with one the first day (they like everyone to have a partner/principal/director interaction). The recruiter will call you sometime within 2 weeks with verbal offers and further directions.