I agree with the person above me; I think it varies per state.
I know the information you were given is correct in terms of current residency for college after a move -- with most states (your's included) you need to wait one year before you're considered a resident of that state in their eyes, and only then will you receive the in-state tuition price. Some states, I've found, require a two year wait.. which I think is dumb. emotion_donotwant
Anyway! I'm not sure about "reverse residency," so you should definitely speak to your college in Florida. Call up either admissions, bursar's office, or financial aid.. one of those should be able to let you know. Some places "sever" contact with people who move out of state, so if your college in Florida is one of them, you may be caught in limbo for a year, until you can begin classes in South Carolina. Good luck, though!