<p>What is the average time that it would take a complete novice, whose background is mostly Windows XP, to go through the FreeBSD handbook and get sufficient mastery to setup a server from the ground up?</p>

It would depend on how much knowledge you have of unix, and from the sounds of things, you probably do not have a whole lot.
Assuming you have little knowledge of unix at all, I would say that it will probably take a few days to get a grasp of what is going on, and possibly a week to have something working.
The FreeBSD handbook is pretty detailed though, and does provide you with a good grounding of everything you need to do to get things to work.
I know that this sounds like an awful lot of time, but in my experience, they really are quite different OS paradigms.