The first week of October has been a really good time to visit Disney. It is great for swimming and the heat is not as bad as in the summer, so it's wonderful for the parks as well.
My wife is a native Floridian and I have been here in Orlando for the last 26 years. We usually have a cold snap come through right around Halloween, but not nearly as early as when you are coming.(Of course this will be the first year for an early cold snap). I hope I didn't jinx it for you. Ha!
HAPPY VACATIONING,
Tom