I found Epic through my university's career education website, applied online in early February, and shortly after I received an email asking that I take the Rembrandt Personality Test. I think this was just a basic screen to see if you'd be a good fit for the position you just applied for. I heard back from HR two days later to set up a phone interview.
The phone interview was somewhat short (30-40 minutes) and consisted mainly of the interviewer, who was a Technical Services employee, confirm the stuff I put on my resume and talk about his position, making sure that it was still something I was interested in. Wasn't really much of an interview at all really, other than a couple of generic questions like "Where do you see yourself in five years?" It was mostly just a screening round to see if I was actually serious about the job. About a week after the phone interview they contacted me inviting me for an on-site interview. Apparently other reviewers had to take a proctored programming test before they were invited on-site, but that wasn't the case for me. I'm not sure what the deciding factor is...oh well.
Anyway, the on-site interview is a total marathon, so be on your A-game. Caffeine is your ally on this day. Just like the other reviewers said: you're flown in the day before, put up in one of six hotels downtown, invited to dinner with a current employee (if you so choose), and then interviewed ALL DAY the following day. Then you're whisked back to the airport immediately afterward.
I was interviewing alongside at least two dozen other candidates for all different positions, and we were kind of led around like sheep all day. It was weird. On the plus side, the whole interview process is very structured and organized with frequent mini-breaks in between portions, so it won't get overwhelming. On the other hand, it's nine hours of tours, interviews, presentations, and computer assessments. Each agenda varies from person to person; during my phone interview I expressed interest in the Project Manager position, so during my on-site interview I had to give a short presentation to a panel of employees, but no other Technical Services candidate had to. Also the programming assessment is by far the hardest part of the interview, and it's at the end of the day for most people. Beware! I wasn't able to finish the last question on the programming assessment in time, but they were like "Oh that's fine, it happens a lot. We'll just set up a proctor once you get home so you can finish it there." So no worries.
HR told me they would get back to me within a week, but I didn't hear back for almost two weeks - likely because I told them I didn't have any other outstanding job offers. On the flipside, a friend of mine told them that he did have another job offer, and he ended up hearing back from Epic before he even boarded the plane to go home. So I suppose if you were really eager to hear back immediately, you could just tell them you have an outstanding job offer...