I don't think a guy should get married before the age of 26 or 27 (they are still immature at the age of 21)
As per religion there is not pre-requisite called "able to support family" in deciding marriage..
you know what if a guy indulges in adultery due to his genuine need , the parents are responsible for this act.. this no one knows.. other wise 26-28 is a good age..
my myself got married at the age of 27...
but for a marriage to succeed the attitude is more important than age..