I waited about 6 months. I'm also 30.
I had a two year long relationship in college, and it went south.
But the thing I'm wondering about is how you view relationships. People are imperfect and people change. When you're in a relationship, you either have to accept imperfection and be flexible enough with (at least most kinds of) change to work through it, or you can't stay in the relationship. That's what marriage is about, IMO. And I love my fiancee, but I also know that we can work whatever it is out as we go forward. She's not perfect (and I'm sure she would readily admit that I'm not perfect, nor even perfect for her, either), but we know that and grow with it. Our relationship just keeps getting stronger because of it, I think.
Waiting 5 years to get married is just a self-fulfilling prophecy for destruction. Either commit to the person for life, and be willing to work through whatever comes (even if you're not particularly happy for relatively short periods) or not.
That's the best advice I can give. Maybe my perspective will change in 5 years, but well, ask again in 2013!