I don't pretend to know when the best age is. It varies from person to person (this includes actually doing it).
My views on it? Well, there's certainly nothing wrong with it. It's a contract between two people, who are choosing to spend their time with each other. I'm not sure if I want to... if I find a woman who I love, I don't see the point of legally marrying. I would, of course, want to have a ceremony to symbolically connect us. It depends. I don't see the point of doing it legally unless it's financially beneficial. I do not pretend that love can last forever, and I would hate to go through legal proceedings if we should separate. Of course, if the woman chooses to stay at home, instead of pursuing a career based on our agreement, I would feel bound to sign a contract with her to divide the assets in case of separation.
Idk, it's complicated.