What age for crib sleeping

Breanne • Baby girl due March 24th, 2016! 💕
When did you let your baby start sleeping in their crib? Did they take naps in their crib before they started sleeping through the night? I'm just wondering if I should even bother removing the mattress protective plastic, put on the bed skirt, ect before the baby is born? I was thinking about having baby nap in her crib to get her use to it. Advice please! :)