DD1 was 18 months because I was pregnant and due 4 months after that and I didnt want her to think I was kicking her out of her cot for the new baby so we did this on purpose.

DD2 was about 22 months old she was trying to climb out of her cot which was a bit dangerous.

DS well he shows no signs of climbing out but he is a big boy so im not sure when we will transfer him, he has a thomas bed for his birthday its a full single bed but low to the ground so im thinking he will be in by 18 months too