To me the theroy of waiting has a lot to do with age. Some can handle it pre-25, some can not. Most people are such a mess they have a hard time telling you what day it is. Get schooling out of the way, get a job, etc. Then look at being serious.
Personally this was learned the hard way. Spent way too much time and money on the High School sweetheart only to find out I was funding parties and suck you off sessions while she was away for college. In the end I did what I wanted, got a little smarter, experienced a wild aray of things and still turned out to be a decent person and Father.