I don't find the 5 hour difference too bad and indeed for the first few days, I actually embrace it. I know I'm not going to have the stamina to stay up to watch the fireworks or be at park close at the beginning of the holiday, but at the same time I know I will up nice and early, be able to finish any unpacking that I didn't get done on arrival day, have a leisurely breakfast somewhere (probably IHOP as it's open 24 hours) and still make it to park opening to beat the crowds.
But as the holiday goes on and I want to start staying up later, I find the best thing is to keep myself occupied. The worst thing you can do is go back to the hotel and lie on the bed - you'll never want to get back up! If you have to be in the room then only sit on a chair (the more uncomfortable the better!) and force yourself to watch TV or something like that so you don't drift off. If you can, go for a walk around the hotel grounds or go out to get a meal or visit a local supermarket - even if you don't buy much, it burns off time and keeps you awake for longer.
Funnily enough I find the jet lag on the way home to be worse with a 5 hour difference than an 8+ hour difference. I think that's because the Orlando flights typically take off around 6-7pm, then they serve dinner and straight after switch the lights out and expect you to go to sleep. I'm not a person who does sleep on planes but even if I was, I wouldn't be sleepy at 8pm. By the time my body clock is telling me it's time to go to sleep, they're switching the lights back on and serving breakfast cause we're 90 minutes away from landing. So I arrive home with jet lag AND no sleep - a killer combination!