I'm taking a Drop Pod as a Fast Attack choice. All of the units can take it as a dedicated transport, but by taking it as fast attack to I gain flexibility in deciding who uses it?

I've got three units that could be advantageous to deployed out of it.
Death Company Dreadnought
Furioso Dreadnought
Tactical Squad with flamer and Heavy Flamer

Before the game is the Drop Pod just hanging out waiting for me to decide who gets to ride in it?

Is it cool if I choose after seeing my opponents army?