I'd like to offer a different opinion on the "the sooner you apply = the more roles available" concept.
If you have a very strong interview, it isn't going to matter when you apply. They are going to offer you something.
they are recruiting from February through April. they are not going to fill all positions in February and when April rolls around spend the money to travel to a campus and hold a presentation, and then tell those kids to go sign up for an interview, and then say "sorry, we don't have anything now".
Yes I know that some people may have been pended and were told that they needed to wait and ultimately were told that they didn't have anything for them, but i think if someone was a strong interview, they wouldn't have been pended (but obviously they weren't a horrible interview or they would have been turned down immediately).
The one advantage to applying early is that you will have your notification that much earlier. Which means that you will be able to start prepping for WDW or you will have time to seek out other internships or jobs for the summer or fall.
It really us ultimately up to how you do in your interview. Each year there are people who psyche themselves up, apply on Day 1, and then get declined for whatever reason. they aren't going to offer someone a job just because they applied early.
my advice would be to study the roles. pick out the ones that you can see yourself working in and focus on those. don't say you will do "anything" just because you think that is what they want to hear (they don't). Don't say that you will do any job that you don't want to do because you think that is what they want to hear.
I know that some will disagree with my viewpoint and that is OK. This is based off of my program experiences, being a rep, what I've seen on here, and staying in contact with the recruiting over the years.