I already sent an update letter in late April.. How soon is too soon to send another update?
Monthly is the recommendation given in waitlist letters. It's not a bad rule of thumb.
Someone asked about 2nd interviews. They are very similar to what your first interview was (hopefully!) like. Low stress, chatty, friendly, and just talks about whatever you've done insider or outside of medicine and about why you like Columbia and why your interviewer likes Columbia.
So a good question came up recently about pre-studying. Now undoubtedly there are those reading who are considering doing it for a variety of reasons. Some have been out of the education game and are nervous about getting back into mental shape, some are hoping to front load, and I'm sure quite honestly many of you are just plain excited to start your medical career. So with that in mind I hope to give you some pointers on things that will, at the very least, not be total wastes of your effort. I will preface this by saying that I did not pre-study anything nor did I have advanced knowledge in anatomy, histology, physiology, microbiology, etc like some members of my class. My performance, nonetheless, has always been proportional to my effort and I have not found myself at a disadvantage because of my lack of previous knowledge. Don't feel obligated to pre-read, nor do I really encourage you to (enjoy your summer!), but like I said some will for a variety of reasons and you might as well get some small thing out of it.
I'd buy a batch of Netter's flashcards and begin memorizing the stuff if you've never had anatomy before. I didn't do this and I was fine (never took anatomy), but it's the one thing that I can confidently point to and say that you will be expected to learn and will make the transition easier by at least ensuring that you are familiar with some of the words even if you aren't 100% able to remember them all. Start with muscles and bones, ignore specific attachments unless you hate yourself and just generalize what bone each tendon is attached to. After that, hit up nerves and vasculature then review it all. I'd focus on the upper body and neck, because that's what is first and thus that's what will be freshest in your mind rather than, say, cranial anatomy which you won't get to til December. Like I said though, ultimately just having the words sound familiar is a good achievement. Other than that, you could maybe pick up a histology book and get your head around the basics. The trick in my opinion is to go for general, not specific. Specifics are forgotten where as the general stuff will be there for you to ground yourself in. I don't recommend any specific histology book (it doesn't matter because there aren't assigned readings), just go for one which seems to have really nice pictures. Other things you could consider doing besides anatomy and histology would be EKG reading. Once again, I did fine without learning before hand but its a skill that is always nice to at least know what a QRS is when you are shadowing and on your clerkships and for pharmacology.
This book:
http://www.amazon.com/Rapid-Interpre...3505346&sr=1-1
Seems to be the Columbia favorite. I have a copy myself and plan on reading it as review this summer because I really enjoyed the EKG section. I learned EKG reading from this book, the required text for cardiology, which is great for the basics and very good at making sure you understand them but I assume the ekg book takes it to a more extensive level. Like I said, I haven't read it.
http://www.amazon.com/Pathophysiolog...3505441&sr=1-1
so jealous! nice that you got an acceptance right off the bat. continuing to wait over here. 
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