Well the class starts in october according to what they told me. And so does the position. So i. Am not sure that it would take 3-6 months to hear back. Its been an ongoing process for the last 6 months or so.
I doubt it's going to take that long to hear back... It might go past the 3 weeks though. It depends on the number of applicants who tested well. If they had more people pass the test than they had positions open, then they have to sit down and go through their notes from the interviews. There are also several levels of approval that have to occur before they can extend an offer, so be patient if they don't know anything yet.
That being said, don't stop looking elsewhere!! I made that mistake when I thought I did really well at an interview and ended up finding out a month later that I didn't get the job. Keep looking and applying for jobs that interest you, if you get an offer from the job you already interviewed for you can always withdraw your application at the other locations.
Best of luck, and keep us informed!