P.M.
My daughter is 4 1/2 mo. old, and her legs are already hanging out past her car seat, she is quickly growing out of her seat though, but we ended up buying a convertible car seat one of the biggest they make because her legs were so long. She could probably stay in her infant one for 2 more months, but her legs are so long it made us nervous so we got the convertible which gives her a ton more room.