It's on Disney's website Calendar. When you view by calendar you can click on the days and it will show what parades are going on.
In May it's only shown on Tues, Fri, and Sat. This is our dilemma. It sounds like a nice thing to see but I don't know if we can fit it in. We definately want to see Wishes which does occur every night at least. If it supposedly is crowded on Tues, Fri, Sat that leaves Mon, Wed, Thurs for us to visit MK. Mon is our arrival day and we planned to go to MGM. Then Wed they have EMH morning AND evening. We actually planned to go in the evening. Thurs may be least crowded during this week since there isn't an EMH for MK, no spectro and EP's EMH day.
Oh, the choices

It almost seems like no matter what day I pick it will be "crowded"