How early is too early to propose?

In my opinion I basically have the same relationship only we are both already in california, been together for three years, and he is getting ready to graduate in about a year and I know that I think about it all he time. I'm 19 and I know that I want to be with him so I don't think it's too early. A lot of people will sit and give you divorce rates and stuff because statistically the world thinks people our age don't have what it takes to make it, but what many people have yet to figure out is that your age doesn't matter, if you have what it takes then you will make it end of story. If you feel in your heart that it is the right time the pop the question :]

Well, I don't know exactly how old you are, but I would definitely say anyone under 21 should wait. Once your over 21 then it becomes more of a case by case situation of how mature both parties are, how strong & healthy your relationship is, your position with school or work, etc. Obviously once you get married there will definitely be sex and when your doing that (protected or not) there's always a slight chance of children. You have to consider income and stability and your readiness with yourself to be that guy who is with one woman for the rest of your life, to be a daddy, or to be the guy that can't go party with his friends all the time after work or on weekends because he now has a family at home.
I know it sounds critical but I know this all from experience. I got married when I was 18, just out of high school. It was a big mistake! Even though we were in love, we weren't ready for everything that came with it. Three years and 2 kids later we ended up divorced. We were separate for a couple years and then go back together, we are now ready to make this work. We're older now, more mature, stable, etc.
Either way Good Luck!

in my HONEST opinion I do not think you should be thinking about marriage till you are about the age of 25 and that is when you START THINKING about it yes you're in love and all that but for now stick with the current relationship

In my opinion, wait until you're about 30 and have been living together for at least a full year. By that point any changes the two of you have underwent will be complete and you'll have a better idea of what you want in a woman, which I can say with certainty isn't the same thing you want in a woman when you're ~20. Plus once you get a stable job and things are going well you'll find that you have a lot more options and choice in who you have relationships with, so don't settle for a woman now if you aren't 100% into her. If there's any lingering doubt about how you feel about her or her towards you, then you're not ready.

Remember, you have a 50/50 chance of getting divorced. Flip a coin a few times just to get a sense of how fragile your relationship actually is. The later you wait to marry, the better your chances of staying together.

Depends on how long you're going to stay engaged. The title of your question uses the word "propose" not "marry", so I guess you the marriage is still some time into the future. When you both graduate from college, then there shouldn't be any practical reasons why not propose at least.

However, if I were you, I'd try living together with her for some more time and see how it really works out (6 months really isn't that long). That way you'll learn how to live with each other and work on problems together, and chances are much better for succeeding in the long run. I've seen the phrasing "you have to test drive before you buy", and that certainly applies here.

And one more thing, and it may sound very unromantic, but marriage nowadays really isn't such a big deal. If it doesn't work out, then getting a divorce is not very difficult nor unusual.