DD was 18 months when DD2 was born. DD transitioned into a regular singlebed with a safety rail with no problems. I bought a new bed spread with cool dragonflies on it, and put it in another room. DD helped me put some toys in there and we played a bit and i was talking a lot about the big girl's bed and about how when she was bigger she could sleep in there. After a few days she asked to sleep in the big girls bed. I told her she was only allowed if she stayed in bed! She did, i don't think she ever got out for about 6 months, she'd wake and call out to me! We had DD2 in a bassinet for a couple of months so if she wanted/needed to go back into the cot she could, but she never did.