[Scandia]

Like various people have mentioned, it depends on the age, maturity, and financial/career stability of the people involved.

If you meet at 20 when you are college sophomores or juniors, then the wait can and should be several years long.

If you meet at age 30 when your careers are stable and you know what you want in a person, then you can pop the question after a shorter time. Two years of dating sounds reasonable.

If a 17 year old is mentioning marriage to you after knowing you a short time and you are not even in a relationship, RUN.