I have heard of people being "offered" a date and then not starting on that date for whatever reason. Seems like you may be able to delay it.
As far as the original post, right now start dates seem to depend on IFS complete or not and SNFO or SNA or not. We have a friend who not IFS complete and an SNA and he will start IFS in January they've told him, there are Lt's from the same TBS Co (Bravo) who are SNFO who are in IFS right now.
On the other hand there are some Alpha Co guys who are IFS complete SNA who have no API start date. I don't know of any Bravo SNA with IFS complete that have started API yet, a few might have dates though.
That's all I've gathered from the goings on around here. It can get confusing to try and sort out, but Florida is beautiful, so there's no harm in sticking around for a while and getting paid for it.