I am the mother of 4 boys. Ages 6, 5, 4, 2. First, a small warning. Not every child is the same and your second could be sleeping through the night by three months or not yet ready to leave your bedroom. I had one of each. That said, I wouldn't worry about putting your baby in the same room as your first son. I used to have seperate rooms for my 2 eldest and 2 youngest. The older boys were always fighting with the younger two, really picked on the baby. Then we moved, what a blessing! Now they all have to share one room. AND THEY ALL GET ALONG, most of the time. lol By explaining to them that it was dangerous to give the baby extra toys when he was sleeping, and that they were too big for the crib to hold thier weight, etc. they were able to relax and let little Joshie become one of thier friends instead of a stranger or doll. They also became extremely helpful in getting diapers and bottles from the frige. We plan on moving agian this summer back to a 3 bedroom house. Right now, I think I'll do one a play room and one a bedroom.