You can see by my signature I have done Twirlmania with my girls since 2000, 2013 is the first year I will not be attending and this is because one of my daughters is getting married that weekend.
Either way, be happy you are given your schedule 3 weeks before, we do not get ours until that Friday, and the event for the girls starts Friday night for the majority that are doing any type of solo work, runs until about 10pm, then the beginners/intermediates have to be back at the gym at 7am for it to start again at 8am. They are usually out by 2pm, but if they have any type of advanced routine as well they are there until at least 6pm. Sunday is group work again being at the gym at 7am and some years we have not been finished until 7pm, then other years we have been finished as early as 4:30pm.
I started the first year going in on Wednesday night, spending Thursday at a park with the girls, Friday getting the line up, souvenirs from the competition and resting up. Comp starts, like I said Friday evening, my girls were Beginner so were done by 2, then we would hit the Magic Kingdom for the rest of the day. Of course they didn't have much time in the park because they march at the beginning of the night time parade as part of the competition. The one year that my daughter and her duet partner were in Advanced we were there ALL DAY, as they went almost last. The next day for group work then as soon as we were done, eat, change and head to DHS for the awards ceremony. Sometimes we can be there for the kids to ride RNR and ToT once before they have to be at the Awards. Monday we head back home, we have been lucky that this is always on President's Day Weekend.
Yes it is for sure an expensive trip, I know it normally would cost about $2k for us and we stayed off property most years. However, remember the trip is about the competition, not about the vacation... unless you can spend a few extra days afterwards. I would not suggest really before because then the kids could be too exhausted, and depending on the coach they may have practices up until day the whole group leaves and even while there until event time. My girls did hang with their friends at the park, we did what they wanted to do, rode the rides they wanted to ride... several had their first Disney trip with the group, and some have not been back other than for this trip, some came without parents some with. Sometimes the parents were there but left the kids with the group so they could do their own thing as well... whatever works.