I stopped wrapping DS1 when he no longer liked his arms in (he would fight to get them out) and he was rolling.
If bub rolls on to their belly and arms are wrapped, then they may not be able to roll back.

So I did the same thing as Nai has described above, and DS1 was about 5 months old.

For DS2, he hated his arms in from word go, so I stopped wrapping him at 5 weeks and he has been fine in a sleeping bag since then.