I have used a safety sleep wrap since DS 7mo was about 2mo, mostly because as a very refluxey baby he slept on a slope and it stopped him sliding down the cot - his little legs relaxing at night meant he couldn't brace himself at the bottom and just slumped into a heap! Bless!
Anyway, we still use it even though he sleeps on the flat now. I have tried without and when he wakes up at night he is really alarmed to be able to sit up and crawl. It freaks him out. So what do I do? Keep using it until he is old enough to undo it himself?