When will baby stop being startled when sleeping

My boy does the same too, even till now 5.5months but rarely at the moment. Since his first month he absolutely hates being swaddled so we replaced it with constant contact sleep and cuddles which worked. I suppose he also felt safe in mummy’s and daddy’s arms. You could definitely try that if your LO is still around the 3-4 months age. My boy now prefers his crib hahaha. So when it happens we use bean bag like you did, and also just gently tap his bum bum and tuck his hands back. But we did observe that more or less he will slowly soothe himself back to sleep without the need of our interference too 😯 so I guess theres no deciding when your LO is ready to be unswaddled as all babies feeling of comfort is different ☺️

At around 3-4months. But the sleep patterns change from time to time. Wait till they learn to flip and roll, you will see them practicing it in their sleep 😮‍💨

6 months for mine. She rejected swaddles since one month old, so I simply just pat her bum and back for a while whenever she got startled.

My #2 stop startled from 3 months onwards.