When is it time to transition to a bed?

Is 22 months too early? We want to move our 4 month old from our room to the crib. But we don't want to buy another crib just to use for a short time. I know she'll sleep in a bed but I feel like she'll just be up walking around her room and be crying at the door trying to turn the doorknob. Any tips on a smooth transition. She'll go down in her crib but some nights she stands up crying and calling for us but shes in a crib and can't get out and falls asleep shortly after. But I feel like I won't be able to leave the room without her running to the door to leave with me.... I'm not worried about her being in the room since it is kid proof (not worried about the dresser or outlets or toys-just stuffed animals and books in her room) . First time transition parent just curious. Should I use a pack n play with our extra mattress for her first few nights in a new room? She has slept in it before in other places no problem. But getting her use to a new room that might help or just go right for a bed?