So first of all, congrats! Hopefully everything works out brilliantly and you spend a hell of a lot of happy years together.
I don't really know you, so I'm just going to speak from personal experience here. My ex and I were engaged for a year, but spent that whole time in a long-distance relationship exclusively over texting, talking on the phone, and other means like Skype, Facebook, etc. Only once did I ever see her. It ended up that we decided not to get married, and broke up. Now here's the thing, we were best friends for about 6 years before that, and dated for 3 of them. And the year of long-distance was what eventually did us in, because so much changes in a person's life when you're not around them. Even if you are totally open and talk every day, you're not going to know if you're truly compatible unless you spend real, physical time together.
You do have the advantage of NOT knowing her in the past. So everything you know is current, and not likely to change a whole lot until you see her. But seriously...SEE her. Meet her friends, figure out her body language and see if you're even compatible! Proximity is 9/10 of the relationship, and to go from never having met, to getting married and spending almost 90% of your time together is going to be INSANE.
Anyways, like I said I don't know you, so I'm not going to freak out that much. It's your life, but I'm just speaking from partial experience, and as somebody who accidentally used a very sweet girl in order to get over my long-term ex... I'm sure you both have everyone you know freaking out and telling you this is a terrible idea, so allow me to be one person that wishes you good luck, and hopes that things work out.
I will say, there is absolutely no rush to a decision that should last you the rest of your life.