Checking with inside sources - code names - PC, FC and TC - I  was able to confirm that Apples fall event to announce the next Gen iPhones will be Wednesday Sept 7th at 10:00 AM PT.  Two new versions of the iPhone (4.7" and 5.5") will be announced along with other updated products.  The new iPhones will be available for pre-order at 12:01 AM PT on Saturday the 10th.  And iPhones will start being delivered (put in customers hands) on Friday the 16th.  

Sep 7th - Fall event

Sep 10th - Pre-orders

Sep 16th - Next Gen iPhones in customers Hands. 

The Sept 7th date makes a lot of sense - as it is also the first day of CTIA Super Mobility 2016.  This goes along with past Apple events timed perfectly to take the wind from the rest of the industries sails.  Much more info on this on Ep 400 of Today in iOS - going live later today.