We started to wean our son from his swaddle around 4 months. The pediatrician said it would be a good idea so that he could be free to explore and develop his muscles while in the crib. I was hesitant to wean because he was such a good sleeper and thought that it was all because of the swaddle.
We started by loosening the swaddle, then swaddling just one arm, and continuing to loosen the swaddle. I tried this for naps only first and continued to swaddle him at night (I'd rather sleep issues during the day than at nighttime). As the swaddle got looser, he started breaking out of it on his own. Eventually, he would take naps unswaddled, and we started loosening it at night.
But, I've heard of many people swaddling their babies for much longer.