Nowhere in the rules I have seen a statement about not being able to choose several prestige classclasses at the same time. And since there is no XP penalty when multiclassing prestige, it seems quite outpowered.
Assuming I meet all the prerequisites for several classes and have no difficulties finding a master, I could take take 1st level of 2 or 3 of them and benefit from all the class base powers... Or am I missing something?