I think it depends on what you mean by "do" Animal Kingdom.
If you only mean visit the popular attractions, no you don't necessarily need an entire day.
If you really want to enjoy what Animal Kingdom has to offer, I would say you need at least a full day, if not more. As three adults, you may enjoy hanging at the Dawa bar for a couple of drinks in addition to the other attractions. I know I have...
Everest at night is a totally different, very cool experience. It is now a "must do" for my family.
Park opens at 9am, shuts at 9pm
X3 Adults
Got FP+ for 2-3pm
Dinner for 4pm
Got FP+ for 5-6pm
Got FP+ for 6-7pm
Was thinking water park in morning till 2-3pm
In our opinion, yes. It's just not a full day Park for us. Today we started with a late breakfast around 1030 and went til the 1st JB show was over and it felt like we were just walking around and reriding rides many times just to kill time. We usually only spend 4-5 hrs at AK and that's with a bigger group with kids of all ages.Park opens at 9am, shuts at 9pm
x3 Adults
Got FP+ for 2-3pm
Dinner for 4pm
Got FP+ for 5-6pm
Got FP+ for 6-7pm
Was thinking water park in morning till 2-3pm
Would I have enough time to do Animal kingdom from then on?