Mad props for starting this, P90X will kick your ass in the best way.
However, as someone who tried and failed about half way in last semester, I can tell you what to watch for:
-Over time, you'll probably come to love P90X. However, the one thing that's impossible to love is how much of your day it takes up (especially yoga). You'll need to manage your schedule (especially as midterms and finals crop up) in order to avoid that monster from the depths of hell: 3AM Plyo.
-Try and find someone to do it with. It helps a lot, especially when you think an exercise can't be done and then see that your partner is doing it right. Again, scheduling can be hard, but it can be done if you're both commited enough.
-Know your weaknesses. I always had trouble with Saturday workouts because I'd be hungover from the night before. Eventually, when my schedule started to get out of wack, I adjusted it so that Saturday was my rest/Stretch day. That fixed everything.
-If you start to miss going to the gym, you can print out the worksheets and go do your resistance workouts there.
One last thing that it pains me to say: Know when (and how) to give up. P90X requires a total of two hours out of EVERY day. As a college student, it's important to maintain priorities and realize when something is cutting too much into study time. I stopped last semester not because I couldn't keep up, but because my grades began to slip as a result of having 10 hours less study time each week (I also had a lot of hard classes, so this semester I don't anticipate as much of a problem). You can also cut certain workouts if you don't want to give up entirely (although for each workout you remove, reserve that day as a rest, you dont want to do certain days back to back).
I'm actually starting P90X back up this coming week. From one P90Xer to another, Bring It!
Well some people try to pick up girls
And get called assholes
This never happened to Pablo Picasso
He could walk down your street
And girls could not resist his stare
So Pablo Picasso was never called an asshole
Not like you