Well, as I do agree that your child should be able to remember going, I will say that I have seen newborns down
at Disney. DH and I went in September before we started TTC, and we saw children of all ages down there. Now, I have only been to the Florida parks. They do have areas for breastfeeding and changing (presented by Nestle, I think). If you are staying at a Disney hotel, just be aware that you will need to fold up your stroller, if you are using your own, while on the buses.