Aye, I see no wrong with being super hyped and buying a littman. If you have to buy your own equipment then I wouldn't recommend choosing something of lesser quality or holding out until last minute. You're probably going to start doing vitals within the second or third week (or you may have already started on the first day of class, but they usually go over legal + ethical issues w/ your well being on the first day and then you run out of time) so having the littman would be a good idea. I can understand being excessively hyped where you get in the way of your own learning (and others) by interrupting the instructor, being too nervous, etc., but I don't think being hyped is a bad thing. I know that I am totally stoked and hyped about what I learn at school, I go to every study group I can, and I am always more than glad to help my fellow classmates. I might come off as excited, but to the instructors and other students thus far, they like that I am confident in what I do, enjoy it, put effort, etc., while I am not detrimental to the class.
Good luck, don't be scared, study groups are awesome, and having equipment will help (if you can't take vitals yet).