About a week after I interviewed, they asked for my references. About a week after that I got an offer. So, 2 weeks. Of course then it took almost 6 weeks to figure out salary and start date. Also, it was about 6 months between when I applied and when I was called for an interview. I think there's a lot of variation. My agency is fairly inefficient leading up to the interviews, but once they actually see some people and make a decision, they move quickly.