You'll most likely be fine. Just have patience & make good use of fastpass! get a fastpass and then check the time at the bottom of your FP. When it's that time, just pick up a new one. Fastpass will make it easier for you to see most of the popular attractions. Have fun!
You've got plenty of time. As TDLFAN used to say all the time--JUST GET THERE EARLY. About an hour before the Parks open, and grab a piece of pavement and write postcards or something until they open. And then run.
Have an idea of those attractions you want to do because they're one of kinds or different than the US and do those first thing before things get crazy--you'll also feel like you got a lot accomplished by noon that way.
My advise on the Parades, is the crowds start sitting for them way in advance. However, I waited till the very last minute and then slipped under the rope and stood in the back. And I'd have a perfect view because everyone was seated-this way I was able to continue doing things up until the last moment, and also was able to move and follow the parade if I wanted.
You'll have a wonderful time. We want a trip report when you return with lots of pictures.