About 18 months because she just decided she hated her sleeping bag one day and wouldn’t put it on
We’ve just introduced a pillow last week at 2yr 2m, and tried duvet too but he didn’t like it
At 2 because he was refusing his sleeping bag
I moved my boy to a single bed with duvet and pillow at 12 months. He mostly curls up on top of the duvet though, will sometimes use the pillow too haha