From January through the first week or so in May you will have teens with Big Tour Groups, Cheerleaders, Marching Bands, Middle Schools, Graduation trips, Sports Teams ...... every single week and weekend. There is no way to avoid in the parks when they are there but you can potentially avoid in hotels. #1 location is AllStars, secondary locations are POP and CBR. As an example this is just some dance/cheer groups that I found heading down in 2015, doesn't include any of the other groups. Note these are their competition days, many events sell before or after packages so they can stay and enjoy the parks.
Jan 16-18 World U Cheer Championship
Jan 19 USA Cheer Tryouts
Jan 19 Florida Dance Championship
Jan 31-Feb 1 National Dance Team
Jan 31-Feb 1 International All Star Championship
Jan 31 – Feb 1 World School Cheer Dance Championship
Feb 7-8 World School Cheer Championship
Feb 13-16 Twirl Mania
Feb 27-28 Studio Dance
Feb 27-28 School Dance and Drill
Feb 27 – March 1 Contest of Champions
Mar 1 All Star Cheer & Dance
Mar 1 School Cheer & Recreation Cheer
Mar 7-8 All Star Challenge Cheer & Dance
Mar 21-22 AmeriCheer
April 10-12 Spring Dance
April 23-24 World Cheerleading Championships
April 25-27 Dance Worlds
April 25-27 Cheer Worlds
May 1-3 Summit All Star Cheerleading