Ferd,
I haven't seen the JCBA on this but our last contract says you have to move to within 125 miles of base and establish your permanant residence. If your current residence is already within that distance, no go. Your new residence also has to be 50 statute miles closer to base than your former residence. If you move under these terms (and a couple of others, these are the major ones) you are committed to staying there (at the base) for at least 24 months or you have to reimbuse moving expenses. The move is good for 24 months from date of conversion to new category.
To the best of my knowledge the above is correct. There are, of course, many little caveats but these are the major points.
Denny