If you don't want to wait and don't mind the drive, Drift Spot is running an open drift day next week (May 18th), and will probably run another full clinic in June (June 22). Here is the list of events:
http://www.drift-spot.org/events/
Also, the pavement at ADSI is pretty rough. We've looked at drifting there in the past and decided that it wouldn't work for most of our drivers. As for an instructional, there should be enough clean pavement for some donuts and stuff.