Obviously this is a significant decision, but probably one that's less critical to make "correctly" than it seems. Whatever you do, it'll work out somehow. I don't have a lot to say about most of the factors involved, because you'd know better than I, but I have some (read: a lot) of experience in academic shifts.

I'm an army brat and wound up going to three different high schools. 7-9th grade was on an American military base in Germany, 10-11th grade was in Virginia, and 12th grade was in New Hampshire. Moving before your junior year would be significantly easier than moving before your senior year, but I didn't really have any problems anyway. Of course, I grew up moving from place to place, so I was used to making those kinds of adjustments, but still, I'm quite sure the prospect of making the transition is more daunting than the transition itself. I don't think it's all that necessary to "establish yourself" before applying to college; whoever your teachers are at the time will know you well enough to write recommendations, so you're covered there.