Our boys shared a room from the time Ollie was 1 year old (before that he was in our room), so Flynn would have been 2 and a half. They have adjusted really well and now fret if the other isn't there. Rarely do they wake each other - even with throwing up sessions, screams, nightmares and midnight trips to the loo. We have room to move them to their own rooms later if they need it, but for now it's fine (they are only 18 months apart so don't really have a personal space issue at the moment).