For a frame of reference, I started this program (lifting, diet, supplements all at the same time) 3 weeks ago. Since then I've put on around 10-12 pounds of muscle mass, upped my bench 15 pounds, my deadlift 20 pounds, and my squat 60 pounds (I had a really weak squat from neglecting leg work for far too long).
This kind of gain isn't commonplace, it really only can happen if you're new to lifting in general and really bust your ass the proper way. So my advice is take advantage of it while you still can, it's not the kind of thing you can replicate later in your career.
Physically I haven't changed much, except my chest and shoulders are a bit larger and more defined and I have
much more definition in my quads now. That and an extremely heightened feeling of confidence to go along with it. I've also shed a bit of fat off my stomach, though that was never really my intention it just kind of happened. I think you're really going to see more strength gain than size doing this.
It's not something that you stay on for the whole three month period. Get 4-6 weeks into it and move onto something else. It loses it's effectiveness after this period of time anyways due to habituation. If you keep going you're really going to just wear yourself out to the point where you seriously risk an injury.
Cycle it up, do some arm/shoulder/abs/calves/glutes work for a few weeks, throw some cardio in there, and then come back to it a month or a couple weeks later and try and put on some mass again.
Regarding the food, the 4-5000 calorie thing really is ****ing hard to obtain. I usually do around 3500-4000 cal/day of good, wholesome foods. The 4-5k thing is more of an overambitious goal to shoot for (unless you are a serious powerlifter, in which case you probably throw back that much food no problem).
Don't be afraid to up the weight! I find myself lifting much more weight than I thought I could simply because I said "what the ****," threw the plates on there and went for it.
And if you're going to do this, be SMART and SAFE! Use a spotter, and don't get lazy on form and hurt your back or shoulders, either. Seriously, it's important.
Anyways, I don't think there's any program in the world where you have to worry about getting TOO big, if there was I think everyone would just stick to that all the time
Good luck, let us know how if this goes if you decide to use it or something similar.