Garrisons are based on where you live, so if you'll be moving a lot, you'll be changing garrisons a lot. The nice thing is you'll get to know a lot of people in a lot of different garrisons! Just put in the request to be transferred whenever you move, should be no problem, just a little bit of paperwork on the back end, is all.
You can use the main unit listing on the 501st website to figure out which garrison you'll be in for any given location. Wherever you live now is a good place to start!
https://www.501st.com/members/displayUnits.php