Hello Bruce! Nice to have you visit us at the Disney Parks Moms Panel with your planning question. It looks like you have a trip coming up in springtime! Your question reflects a good Disney-vacation planner!
Based upon personal experience, I have found the four Disney Parks to be less crowded from park opening until about 11:00AM and then from about two-hours before park closing until closing. To avoid crowds, I encourage you to take advantage of
Extra Magic Hours. Each day, at least one of the four Disney Parks is open before or after regular park operating hours. This is a special perk for Guests of Disney Resort Hotels. My family and I always take advantage of this great benefit. We spend our early mornings in the park, head back to the resort to enjoy the pool (or a nap) and then head back to the park for the night. We find that this strategy helps us to avoid the largest crowds and the heat of the midday sun.
Bruce, if you really want to experience the Disney Parks with very low crowds, I encourage you to take a look at the special-ticket
Disney After Hours events held Magic Kingdom Park or Disney's Animal Kingdom. These experiences provide a limited number of Guests with the opportunity to enjoy the parks with limited waiting time for attractions. The admission price also covers complimentary ice cream, popcorn, and select drinks. Good news, there are dates available around the time of your stay in May!
Feel free to come back and visit the Disney Parks Moms Panel if you have any additional planning questions!
Hakuna Matata! Jonathan G.