My son slept in the my bedroom in a small craddle until he was about 6 months. The main reason for this age, for me, was when he started only having one feeding a night. That also was the time he started sleeping through the night. I was lazy and didn't want to go to the other side of the house to feed him multiple times in a night if I could have him right next to my bed. :) We also used a baby monitor since the day we put him in his room. Don't know if I would have felt safe having him in another room if I couldn't hear him. But I LOVED when he wasn't in the room anymore. We didn't have to worry about being so quiet when we went to bed or hear him rustling around as much.
Good luck with it.