Further, we also notice that the dates keep going back. 12 September 2012 > 10 September 2013 > 9 September 2014 > 9 September 2015 > 7 September 2016.
I'm putting my money on Sept. 6. Further the MWC date has been known for a few months now, so Apple must have been aware of it. Unless they don't give a **** ...
it would make sense if it's the 6th with your theory of the dates going back, the 6th is a Wednesday and within Apple's usual Tuesday - Wednesday event frame (at least for iPhone announcements). Tho the 12th has been mentioned but I'm not sure how reelable this rumours is, last year Even Blass leaked the date and he was correct.