I moved out of my parents house when I was 24, which was 3 years after I graduated. My gf, who became my 1st wife, graduated two years after me, and we got married a year later.
My mother started charging me rent, a very small sum. I remember fighting her big time on that, but in the end, when I got married, she gave me the money back. She was worried I wouldn't save it for myself....and she was right, so good move.
My stepson was home for about a year after he graduated college, and then he not only moved out, but away.
My oldest son (who is special needs), who turns 17 in a couple weeks, will likely live with us as long as he can. My 15 y/o, will likely move out as soon as he can.