It depends on the person and what they’ve been through. But I would say in general, most people are not ready until they are 24-25. I was 22 and wish I would have waited a little bit longer. My plan was to wait until I was 24, but we had already been dating 3 years and knew we wanted to get married someday. My dad, who I was living with at the time, decided to get remarried, and his wife inconveniently moved all my stuff out to the garage one day while I was at college. When I came home I felt I had to move out but I still had a semester left of college so was only working part-time. My then fiance was working full-time but we both DID not want to live together before we were married so he bought a mobile home and helped me pay for it for a few months until we got married and he moved in (he was still living with his parents at the time).
I would have loved to live by myself for a year or two but everything just kind of got pushed on me to get married. I am glad we waited 5 years to have our first child though. We got to do a lot of fun things as a newly married couple as well as buy our first house. I think that having kids matured me WAY more than getting married.