For the bionic release this is sort of like chatter that the NSA tracks with terrorist. With all the rumored dates we know they are getting close. If you look at it this way there is a lot of logistics that have to happen between final test approval and actual launch. They have to make final. Updates from test builds to production builds (remove bug tracking and other test sw, an probably lock the boot loaders), then they have flash that final build and ship to the brick and mortar locations. So at this stage they probably have a few dates being thrown around depending on the final testing. So say they have a bug and they are getting a fix they are probably calculating how long to test that bug, how much regression testing isneeded and if the bug is resolved with no new issues how long to get the devices to stores and launch. Based on the fluidity that can occur at this point they probably have several dates circled on a calendar somewhere. If you work in IT, you know how this goes.