A change of residence just for USNA nom purposes is more complicated for college students than you might think. There are typically five elements of residency: (1) where you own / rent a home, (2) where you pay taxes, (3) where you are registered to vote, (4) where your car is registered, and (5) where you have a driver's license. The more you have, the more likely the old and new state will recognize the change.
Generally, you can't establish residency until you have proof of a new address. Proof includes a rental agreement or utility bills in your name at the new address. That could be difficult to do if you're in a college dorm but, in any case, it will be hard until you're actually on campus. Ditto with driver's license and car - and that's if you have a car at college -- most freshmen don't. Yes, you can register to vote, but that alone doesn't create residency.
A complicating factor could be if your parents claim you as a dependent on their taxes. I'm not a tax advisor, so I don't know whether/ how your establishing residency in another state affects that, but you and your parents should figure it out.
If you're applying for a nom, you would have to wait until you have established residency in the new state to start applying. Many MOCs have deadlines in Sept. or Oct., and you may not have time to get residency changed before applications are due. Also, MOC committees aren't stupid -- how excited are they going to be to give a nom someone who established residency in their state less than a month before and (if they get the nom) will likely leave their state in a few months?
Per the above, colleges often will not give you in-state tuition if you change residency after showing up -- o/w they'd be giving all upperclass in-state tuition. So check that out as well.
Finally, USNA considers your residency to remain with your parent(s) (or wherever it was when you applied the first time) unless you provide proof to them that it's changed.
Thus, if you want to change residency for non-USNA reasons, then do so if it makes sense. But it VERY hard to do it for USNA purposes.