I'm curious to know how long it takes a Queen to fully mature? I assume longer than 24 hrs. with Ripley's gestation time being, what, a week in
Alien3?
How many weeks between the fall of Hadley's Hope and Ripley and co. showing up again?
The Alien Soldiers wouldn't want to start collecting too early or else they risk everyone who'd been captured attempting escape (or at least just being lousy guests - "Help, help, help me!!" for days on end).
Ahem, or if she wasn't ready for a couple weeks yet, there's risk of the human hosts dying of dehydration or starvation while cocooned.
You think they'd want the Queen at Egg-producing capacity before they start making real moves to build numbers.