Ironically, I was quite worried about this before starting school and now that I'm in school, it's not as big of a deal as I thought.
For one, I'm studying way too much to care about any of that crap. I.e. even if I wanted to socialize, it's not like I have time to.
Second, my lab group's pretty cool, in the sense that they're all decent people. We don't have any condescending types or dominating types. Everyone is good about sharing dissection (for the most part). It's not necessarily true that I see myself really hanging out with them a whole lot outside of class, but I really feel like they're decent people.
As I grow older, I recognize the greater importance of surrounding oneself with DECENT people. It's great to have friends who share common interests and with whom one can truly hang out/do stuff with. But it's more important to have an abundance of trustworthy, good-natured, decent people around. Even if they're quite different from you. (Here's another bit of advice: Give people a chance. I don't know what your crowd was like in college, but try to look beyond what you're used to. Give everyone a chance. Give yourself a chance to socialize with different kinds of people. People who you haven't socialized with previously, perhaps.)
Third, I feel like I have enough "acquaintances" that I feel comfortable in the environment (i.e. going to class, activities, etc.). Granted, my criteria for feeling comfortable is probably pretty minimal compared to perhaps a more self-conscious person. I mean, I used to be really very self-conscious. Now, I'm more into doing my own thing. I count a "face I recognize" (i.e. from some orientation activity or a brief exchange) as an acquaintance. So basically, that's enough for me to feel comfortable. I don't need to sit with a row of friends every class and always surround myself with tons of people. It may be because I'm slightly older than my classmates too. I'm just way out of that college mentality now.
All that's not to say I'm not open to meeting more people. I also DID go out of my way to attend some activities during orientation. As many have said, that IS sort of a critical time to start making those connections. There were some optional pre-orientation activities I attended where I did meet some people who I now am more close to, relative to everyone else I met later. It's just a formative period. I guess people bond during those times.
But it's never too late. And I recognize full well relationships ebb and flow and change. It's VERY early yet. Who I'm seeing/talking with now may change later on. Or it may not. Maybe my existing relationships will deepen.
I don't know. The point is, I'm just going with the flow. I'm focusing first and foremost on my schoolwork. I think you should too.
Also, another key point is... if you do well, you will probably find yourself surrounded by classmates eventually anyway. People love to ask Qs if they find you are a good source of answers.
Remember where you are. Medical school. Like everywhere else in medicine, people naturally respect smart people who do well. It's a natural hierarchy for a bunch of driven, type A personalities. So, if nothing else, by doing well, you will naturally gain everyone's respect. If you're Miss Popularity and at the bottom of your class, I'm not really sure how much value that has to you or anyone else. Aim for the respect of your colleagues by doing well AND by treating everyone with courtesy.
Aside from the respect issue, doing well academically is also a feedback loop. If you DON'T do well, you'll probably feel stressed and depressed, which certainly does not help matters socially. You won't feel like socializing when you're stressed and depressed. And others won't feel like socializing with YOU, either. When you're doing well in class, successful and happy, other happy things (including relationships) tend to follow.
