In the old syllabus (which everyone but the two newest classes is still under), somewhere around three months from the start of ground school to selection. It varies per person, and depending on the time of year; for example, summer in Pensacola is notorious for magic thunderstorms that appear out of nowhere, so less flying gets done in general.
In the new syllabus, which I'm assuming you'll be under, it may be more like 4-5 months; no one's really sure yet, since those classes have barely started.
Personally, I checked into the squadron on 26 September and selected on 15 December, but I moved through at a pretty good pace.