We have been the last two years in a row to USF/IOA on Sat/Sun the 2nd week of December.
ALL rides at USF were walk -ons (even MIB) and the only waits at IOA were Spiderman, Hulk & Dueling Dragons (and those were well under 15 minutes...).
We even did both Parks in one Day on a Sunday...it was that slow....almost a ghost town at USF.
Have FUN!