DD was 18 months old ... partly because we were renovating "her" room. Without the renovations ... not sure. But I know one thing for sure, don't fall for the line that they won't get used to sleeping in their room if you have them in yours. DD now ABSOLUTELY REFUSES to sleep in our bed, even though she did for 8 months and then in the same room till 18 months. I now have to sleep with a teddy because I miss her so much and she refuses to sleep with us.