Having an early housing confirmation is one of those little secrets that nobody tells you, but there are several important things about applying early.
First, obviously, you don’t get shut out. UCF is a huge university, so there is a lot of demand for dorm space. I believe there are about 7,000 dorm rooms on the Main Campus, but I don’t know how they count rooms. (Does my daughter’s Towers apartment count as ONE room, or FOUR?)
You also have to keep in mind that many of those dorm rooms are reserved for various "Living Learning Communities (LLC’s), so a good number of rooms are not available to all applicants.
Second, as @vannevka mentioned above, your housing confirmation date governs your selection priority. You actually pick your room in many cases, so that matters.
Also, once you receive your confirmation you can start looking for roommates. The ideal situation is to have your roommate group set prior to room selection. If you don’t, once you select your room, ANY student meeting the dorm qualifications (contract type, LLC if applicable, etc) can choose any open bed in your dorm.
Third, your earlier housing confirmation allows you to “pull in” friends who apply later. Even if a good friend applies months later, you can pull them into your roommate group as soon as they are confirmed – if you have an opening.