I have 2 kids. When they are a new born BB, they already sleep alone in their own room.
But I will put a walkie talkie in their room, just in case they cry at night.
For BB, you can buy the underwear in MOTHER CARE which can cover the stomache. That's what I do for my BB before. And in my experience, they won't move while they fall in asleep till 6 or 7 months.