BCT in all reality isn't that bad. Obviously getting yelled at sucks, and always being wrong can be miserable at times. The trick is to get your stuff memorized, make your room as good as possible and just put out, 100% ALL the time. If you constantly are motivated, constantly helping out your classmates your cadre will notice.
1st BEAST was kind of boring in an aspect, its a lot of classes and a lot of marching. The days go by a bit slower than in Jacks.
2nd BEAST was a blast, difficult physically, but a blast. You are constantly doing something physical, and I personally enjoyed that aspect of it. The days went by much faster.
I came into BEAST not in the best of shape, I spent the time from when I graduated high school till I left for BEAST hanging out with friends and family and kind of working out. If you can get in the best shape possible before leaving that's good, but realize there may still be a time where you break. I picked up the physical aspect really quickly, so the beat sessions we had turned out to be not too bad.
To answer a few other questions:
I honestly could say I feel as if mentally I was prepared for BCT, and I think I had played it up in my mind to be worse than it actually was. Academically, I am confident that I will do well, I have a decent course load and am cruising through school fine.
I CAN say that one incredibly important thing is to GET AHEAD. I am always at least 2 days ahead on homework, which means if one night I'm exhausted I can just go to sleep at ACQ. My roommate is always doing his homework for the next day, and so if he is really tired then he still has to do all of his homework.
Another tip for incoming freshman, when you get here (especially during the Ac year) sleep! Don't stay up till 12 or 1 every night talking on the phone (if you get them back) or sitting on facebook. You may be able to do that during high school (I would go to bed around 1 and wake up around 5 for track and be fine during school) but it really takes its toll here. Stress, physical activity, everything you have to do as a doolie all adds up and exhausts you.
I finished my application late August, and submitted it early September. I received my LOA early December, and my congressional nomination in January.
As someone else said, if you do get accepted, spend time with your friends and family. It's the one thing I feel like I did incorrectly. I don't feel like I spent enough time with some of my closest friends, but I was fortunate enough to spend quite a bit of time with my family. Don't spend all your time in the gym preparing, if you are from lower altitude its still going to kick you in the butt. I was a track and cross country runner in high school, and the first AFT we did (the second day of BCT) I thought I was going to die. I managed to pass, but barely.
Also, during BCT, if you fail your first PFT or AFT do not sweat it. I did terribly on my first PFT, but we also were having beat sessions and you don't notice how fatigued your body truly is. My PFT went up over 100 points post BCT, and this next one we take this week will likely go up quite a bit as well.
I hope I answered everyone's questions, keep them coming! Sorry it took awhile to respond, I had quite a bit to do this weekend.