Sorry I made you wait for this one. That doesn’t mean it came out better.
Marriage is an investment in many ways, so you want to start the compound growth early. The benefits which marriage grants grow over time, so you want the clock ticking already. This is true for love, which only matures with time (earlier marriages>fewer divorces). And it used to be commonly understood more humans = more wealth.
Generally speaking, when something is the right thing to do, that thing ought to be done ASAP. This goes for every other Mitzvah, too (including Shacharis, which isn’t unrelated): Zehirus brings Zerizus. Rabbi Arush’s “The Garden of Wisdom” is very good at explaining the poor judgment in intentionally extending bachelorhood.
The younger you are, the more patient you will be with children.
Breeding is the original, and still the best, non-government retirement plan for old age. The younger you marry, the more children, and ergo, the better the chances at least some of them will have the ability to help support you. And don’t be scared of raising children; they tend to help raise each other, assuming they are closer in age to one another – which is another reason to marry early.
Bottom line: Pray for yourself and your children they marry early!