Hi, Lorraine! I always tell people that there is no age too young to go to Walt Disney World. My girls are veterans from very young ages, and while the memories made during their early visits may be lost to the kids, they will be my memories to cherish forever.
There are way more attractions that very young children can enjoy than I think most people realize. In addition to things you would expect - like the Jungle Cruise, Dumbo the Flying Elephant, the carousel, and other similar attractions, I always took my kids on things like the Haunted Mansion and Pirates of the Caribbean. At that young of an age, they didn't know the Haunted Mansion was "scary", and by the time they did know that some of the stuff there might be frightening to some people, they were so used to it, they enjoyed it way more than they would ever be afraid.
I took babies on Buzz Lightyear, and into productions like Voyage of the Little Mermaid (a favorite of my then 18 month old middle child, who danced through the whole show and has to this day a flair for the dramatic). The Tomorrowland Transit Authority was a favorite place of mine to grab a bit of a breeze and relax in a calm environment as we got ready for nap time.
I never hesitated to take my girls to Walt Disney World. I love every picture I have of their early visits, and I love sharing the memories with my growing up way too fast daughters!
Have a great vacation!