I feel like a lot of people are needlessly stressing out. Most of the interview invites are for dates that are 5 to 6 weeks out. I'm sure they going to slowly fill those interview dates over the next month or so as more applications are completed. I know people last year that didn't have their secondaries done until the middle of August and still got early September interviews (especially if you live in Illinois, I'm an illinois resident). I wouldn't be surprised if someone who submitted on 7/15 and another who submitted on 8/15 got the same interview date. My only suggestion (if you haven't done this already) is make sure that your letters are ready to go the instant you get your primary application verified and sent.