Here's a piece of advice widely espoused by the DISers who go with young children: get out of the parks in the afternoon and head back to the hotel for a nap and/or pool break. This works best if you stay on-site.
But the basic schedule that most people like is to be at the park at opening and do as many attractions/shows etc. as possible, then stop for lunch (either in or out of park) and then head back to the hotel for an afternoon break, head back to a park (park hop to a different park, if desired, to see a particular show) either for dinner or just after and stay until after you've seen a night-time show. When you plan to go to Early Entry for a park, make sure to get to bed early the night before.
The parks tend to get busier during late morning and so you'll avoid more of the crowds. When we had just the one young child, I would head back to the hotel and nap with our son while DH would stay at the park and get in one or two or the adult rides. DH would then meet us back at the hotel in time for dinner.
Also, ask to use "Babyswap" on rides that you and DH both want to go on. You can combine Babyswap with Fastpass to avoid long lines for both of you.
Definitely get at least one Priority Seating reservation for a character meal.
Take your own snacks, juice boxes and candy. Learned on our first trip that you can't just buy one small lollipop -- you can buy one gargantuan lollipop or several small lollipops, but not just one small one, at WDW. It's great to have some snacks as a hold-them-over when you've got a bit before mealtime.
Enjoy your trip.