I got a dog my sophomore year, I am now about to graduate. She is like 2 and a half now and I have to say, although I love her very much, it was absolutely the wrong choice.  You may want to study abroad, be able to move about, go out with your friends and not come home for days at a time. none of these these things are easily done if you have a dog.   Also if you are in a labor intensive major which requires you to be on campus for endless hours, that will be difficult with a dog.  Since you are not 21, and don't realize what a draw bars/drinking will be I would hold off.
Now if you have thought about it and truly are sure you want a dog for the next 15 or so years, then yes get one because they bring absolute joy to your life.  Make damn sure that you want that and that you are willing to sacrifice some of the stereotypical "college" experiences.  But if you have pretty cool roommates then a dog will absolutely be a wonderful time for all of you.