I swaddled DS until just over 4 months - he would smack himself in the head if not swaddled. I eventually gave up because he started fighting against the wrap. It was a process to stop - the first few times i didnt swaddle him, he screamed and screamed with his arms by his side - as soon as i swaddled him he fought against it again ! I used to leave one arm out during his day sleeps (both in at night) until he eventually could sleep un-swaddled.

I dont think there is any rule about when to stop - every baby is different, but i know there is some ladies on here still swaddling at 8 or 9 months, so dont worry about still wrapping baby. He will let you know when he wants to give it up.