I was first referred to my employer by a friend. (He got a $1,500 bonus when I ultimately got the job, which is pretty awesome.) I waited for a call about setting up an interview for well over a month. The initial interview was over the phone, very easy, I’m sure they use this to weed out anyone terrible. The second interview consisted of 3 panels of 3 people each. They were pretty short and they asked the standard questions behavioral questions like “tell me about a time when you had to work with someone difficult”. If you google “standard interview questions” and prepare for those, you’ll be all set!
The timing was right, they called me a couple days after the interview because they needed someone immediately. I have, however, heard bad stories about people getting put in the “pipeline”. This means they call and tell you “we like you, we want to offer you a job, but there is nothing available right now. Hold tight.” Someone that interviewed the same day as me (also friends with the person that referred me) didn’t get an offer for about 2 months. By then he had already started another job and was no longer interested. So don’t wait around for them to call you.
Overall, pretty easy and good interview experience for me.