No age is too old. It's a matter of when you want to begin Happiness. That's assuming you have found your perfect partner. If it's your soulmate, try to get started as soon as you can. But boy! You'd better be right!
I believe the ideal age is around 25 because during this phase of life, you get to enjoy a lot, understand each other and then before 30, plan a kid. But I really hate people who marry at later age even though they have everything in life but they give more importance to career. There are quite a lot of examples and samples.