A.
NOW! My son and daughter are 21 months apart and we moved him a couple months before she was born so that he did not feel like she was taking his bed. We put him in a twin bed with guards on the side and made a big deal about his new bed. He still had some issues with wanting to be in the crib with her, but never had a real problem with giving up the crib for her since he had a cool big boy bed. The key is for her not to feel like she is giving up her bed as she will have enough to feel like she is giving up without that added stressor.