Welcome aboard, Jeneane! You are in for so much fun and excitement (and lots of time for relaxing too!) when you set sail on the Disney Wonder this year!
The earlier dining time is the best one for families with very young children like yours. I promise that there is always something fun going on at dinner, especially in
Animator's Palate where your little guy will delight in seeing the room change slowly from black and white to color! I know that guests are able to request a change in their dining time the first day onboard before they dine or even before sailing by calling Disney Cruise Line, however I've not heard of anyone changing times once they've already begun their rotation. it wouldn't hurt to ask onboard though if you find that you've like to change once you've experienced the first meal. However, I think you will really enjoy that first seating. If you find that you'd prefer to put your little guy into the nursery during your meal, feel free to stop up to the nursery to see when they might have openings still available so you might be able to book a few hours.
I'd suggest though, that if you'd like to have a romantic dinner one night, you plan to book him in the nursery and then book yourselves a meal at
Palo (be sure to make both the nursery and Palo reservations as soon as your 75 day online check-in window opens). My husband and I never miss an opportunity to dine in Palo, which is an amazing Adult Exclusive restaurant on each of Disney's ships. There is an additional cost, but I promise it's worth every penny! Your son will be well taken care of in the nursery and you can relax and enjoy this amazing meal and experience!
Have fun planning, Jeneane!