Is the 4 year old yours or someone else's?
Does the 4 year old still nap?
I know a lot of people here swear by the mid day return to the hotel and nap thing, but that never worked for us. Only one of my 4 year olds (I have 5 kids over the age of 4, BTW) still napped. My napper was good napper, so he was able to nap in the stroller.
Since you are there for 8 nights and have 5 day tickets, don't waste a park ticket on the 1st day since you are arriving late. I have found that a good way to get into the "Disney spirit" is the 1st day book a dinner at Chef Mickey's at the Contemporary and meet the characters and then take a monorail ride around MK and Epcot.
I think 4 year old are, generally, more reasonable than toddlers, but they can get scared of things. I would start with the more gentle rides, like Winnie the Pooh and It's a Small World, and work your way up to the "bigger rides."
Like others have said, don't get too focused on having to stick to a strict schedule or plan. You may plan to take it easy and nap and the child may want to go, go, go. Or you may want to go, go, go and the child is exhausted.
Try to keep meal times around the same as they are at home. Nothing is worse than a hangry child. (unless it is a hangry husband LOL)
Along those lines, throw some snacks in the back pack for those times.
Don't be so focused on doing everything that you forget to take breaks and relax.
Aside from 2, my kids aren't morning people. My one daughter is a straight up witch if you wake her up. For us, it is easier to skip rope drop and stay later. For others, their kids don't tolerate late nights, and it works better to get there early and call it an early night.
Most importantly. Potty breaks. We have had accidents because they are having so much fun that they put off going to the potty until it is too late to make it. Our rule is "all for one." If one person has to go, we all go, whether you say you have to or not.
$ is, actually, a really good age. Like I said earlier, they are through that toddler stage, there are no diapers and bottles, and, maybe, no naps, but they are still little enough to believe in the magik.