OOPS...forgot to check your location
If mom & baby have adequate shelter & temps are mild there's no reason why they can't be outside all the time. Momma knows how to keep baby warm, that's what she was made for. As long as your cage/coop has a place for momma to take baby out of the weather & cold when needed they can go out now. A bigger concern would be any other birds you have. If momma is high enuf on the pecking order she should be fine, but if she is low bird the others may pick on her & baby if they go back together too soon.