Hmmmmm. Honestly, I'd do May. Not JUST because of Carsland (tho it's a bonus to have it not be crazy busy because of it)..but because it's cooler weather and in general not quite as crowded. You don't want your first trip to be super hot and crowded! Plus then you have a good reason to go back in a few years
And Bungle- Yeah any opening is gonna be a little busy. At least it's a whole land and not a ride??