Opened my first credit card, a Discover student card, at 18 whilst in college. My credit limit was something awful, $1000 if I recall correctly. But the credit impact was immense.
By charging a hundred bucks or two, and never carrying a balance, I already had a 4 year long positive credit history upon graduation. Fast forward a few years, and I was able to take out a mortgage at 25. The Credit Union that granted it explicitly stated that said length of responsible credit card membership was the deciding factor.
It doesn't take much to build a credit history while you're young, and even $50 or $100 per month in your student years is enough to get a serious leg up.