9weeks first time although not out of choice. He no longer fit his moses basket and we couldn't fit a cot in our room at the time. 2nd time 6months as advised. However it was much harder then! Lol
4 months plus I'd say. It all really depends on what works best for you and baby. Some baby's won't take to their own room for months while others may. My little girl is just over 4 months and I will move her into her room around 5/5 1/2 months x