My 2016 calendar has July 15-17 and 20-23. That would be Gas City, Kokomo, the Berg, THAT, Putnamville, Bloomington & Haubstadt unless the earth shifts on its axis. Last year, or sometime, I did an analysis of several years and gave the rules I think they follow. Right now I don't seem to be able to search for all of my own posts, but I will keep trying. A guess is that the Smackdown will be August 25-27. The big $50,000 to win wing and nonwing shows are at the Badlands Speedway the week before and I don't think they would run against that, but of course I could always be wrong. I'll try to ask around the pits in Tucson tomorrow.
UPDATE: Found it. Last year I posted that since 2007 ISW has begun the second Friday of July. However, in 2016 the second Friday is July 8, which would make ISW quite a bit earlier than usual, thus the July 15 starting date.