just got back from our trip and we were chosen to be in the parade at MK. It was exciting (for my DS7 especially).
We were waiting in line at will call to exchange one of our vouchers for FP's and the cast member directing people which line to go in struck up a conversation with us as to what kind of volunteer work we did for GAD, etc. He told us about the parade and asked us if our family wanted to take part. There were 3 families asked in all.
We were not there first thing in the morning, i would say maybe 10am. I would inquire at will call or inside the park at guest relations.