If I were you...
...I would hold off on setting a date. At this stage of the game, you don't know where you are going to be or what you are going to be doing next week, nevermind next year. Heck, you saw how folks on this board (who are in the "flying" part of flight school) had to wait until pretty much last week to find out what this Christmas leave dates were going to be!
If she is "the one," she'll be there after you get winged, and you can set a date for when your future is a little less "week by week." I would wait until my future was somewhat certain, and when I'd have time to immediately take her on a nice honeymoon (trust me, it is worth it). Your wedding is not something you want to squeeze in during a long weekend, if you have the option.
It sucks, but even in the benign world of the training commands, schedules are day-to-day. I'm not there yet, but it sounds like the RAG is the time to do it. The nature of Primary and Advanced (the pace, and the fact that you are basically just a "number") does not give you the flexibility you need.
(Nobody read into the "number" comment - training is professional, and you are an individual, but let's face it: When there are hundreds of students that need to be trained in a relatively short time, the staff can only help you out so much.)