Does it say anywhere in the rules that when you Drop Pod, Deep Strike or Summon Demons that it occurs at the start of the round?
I played against a guy who made his reserves rolls, moved units around and then drop podded in. It didn't matter to me because he was making mistakes about where he was deploying ( dropping stuff in front of tactical squads...), and you never interupt your opponent when he makes a mistake.
But this got me thinking, and I've never seen a rule that says when you bring the units on.