Just got back yesterday, and were there for 3 days. WWOHP was open just about the entire day sat, sun and yesterday, and early entry from 8 to 9 is solely for resort guests, but none of the rest of the park is open.
We waited in line for Olivanders for about 30 minutes and waited for 40 for FJ.
We went back on both later in the day both days with no line.
Olivanders is something you will do once, unless, you want to try and be picked, which is difficult.
FJ is something you MUST do through the entire cue the first time to see the castle.
If there is a line at olivanders skip it and go on FJ. if the line is short, do Olivanders first.
Single rider line for FJ takes less than 10 minutes. Once you've done the castle, if you go back on Fj, do single rider.