J.P.
Hi! My daughter's doctor told me that when she flips over to her stomach at night, to just leave her cause she's ready to sleep on her stomach. She slept on her stomach for the first time around Christmas. She was almost 5 months old at that point. When I would put her in the crib at night, I'd put her on her back down towards one end of the crib. When I'd go in the next morning, she's be on her stomach, on the other end of the crib and facing the opposite direction. She's now 9 months old. She starts on her side at night and eventually is on her stomach, knees tucked under and her rear end up in the air.