We're due in December and we'll be moving our 2 year old to a big girl bed as soon as we move into our new house. Our thought on this is primarily that I don't want her feeling "kicked out" of her crib when the new baby arrives, even if it takes us 6 months to transition the baby to the crib. I'd like her to have a least six months of sleeping in her new bed and feeling comfortable before the baby arrives, so she doesn't associate the baby with disruption of her personal space. We won't be pushing potty training because she's not ready and we use cloth, so it's just a few more diapers to wash in the end.
Beautiful baby girl born 8/13/2012. Little star baby lost at 10 weeks pregnant, 12/18/2013. Rainbow baby girl born 12/22/2014.