We put LO up alone for the first stretch of sleep at night from 1 month (he shared our room then so wasn't alone after 11), he napped upstairs from about 3 months and alone all night from 5 months. It's really up to you and when you feel ready. Personally I needed some time by myself and with oh and it kept me sane, I know others don't like it so early. My LO also sleeps far better alone in a peaceful room xx