When to Line Up When There are 2 Parades

[WeatherbySwann]

We will be at MK for the 24-hour day on May 22, and there will be 2 performances of Festival of Fantasy, one at 12 and another at 3. We plan to see the 3:00 to see the Disney Channel peeps as the grand marshals. How early should we line up? Are crowd patterns similar to on days when there is only 1 parade? Of course the celebrities will add some crowds. I guess a similar comparison might be the Star Wars motorcades. How early do people usually start lining up for those?

I know there are a lot of differerent variables. Guess I'm just trying to figure out where to watch it and when would be the best time to get there.