Based on history, I think this will happen:
* iOS 7 GM released tomorrow. Officially still for developers, but unofficially also "power users" who download it at own risk since it's usually technically identical to the later public release as an OTA update. In a very unlikely chance, it'll be pulled due to some last minute major surprise bug, but not for minor bugs. That's for e.g. iOS 7.0.1. Apple is probably already working for the post-7.0 fix release as all developers release software with known bugs -- the question is when the bugs are acceptable.
* iPhone 5S announced and orderable tomorrow (doh) along with the iOS 7 GM.
* iPhone 5S actually shipping within 1-2 weeks or so, which is in the timeframe when iOS 7 will "activate" as an OTA update for everyone. Again, most likely equal to the GM.
I do think that iOS 7 *may* be delayed for the iPad by half a month to a month or so based on bug reports and that Apple maybe having focused on getting it done for iPhones due to the imminent 5S.