I was going to post the same thing about the "BabyWise" book. It's not only misinformed, but down right dangerous! Do a search for it on the web and you should find tons of information. It's pretty much impossible (and not a good idea anyway) to try to put a breastfed baby on a schedule. Nursing "on demand" is the best way to go, and, at least at first, that usually means nursing pretty much 24-7!

It does get easier, though! If you want to stick with nursing, Kermit's advice about just breastfeeding as much as possible as often as possible is right on target! Supplementing with formula won't be good for your supply at all, and you will probably find out your little guy doesn't really need it. Of course, if that's what you want to do, that's fine, too! If you need any breastfeeding help or advice, feel free to pm or email me.
But, since this isn't a BFing thread, I'll get back on target . . .
I would say that if you feel comfortable with the situation, go ahead. I probably wouldn't have done it that soon, especially since we wanted to wait longer than that to introduce bottles, but I wouldn't think bad of you for doing it.
Our little guy was extremely early and very, very tiny. This was his first winter, so we were pretty much on house arrest because of the risk of RSV. We really didnt' go anywhere from October through the end of March. So, I know what it's like to feel a little cooped up! Good luck!