I've only been working with BC for a couple of years now, but I havent had any problems wiring branches as they start to lignify.  I don't think you want to wait too long because they thicken up quickly, but too early (when they are very bright green) and you might snap them off at the base.

practicing the wrong technique will make you perfectly wrong, get a teacher (aka a good local club member, someone who has good trees, not just because they are old (like me)), take a workshop with someone who teaches wiring (Boon, matt Ouwinga, etc) or use video (Boon's DVD) or internet sources that actually demonstrate wiring. Wiring is a skill, it must be learned, and can only be learned with good information. I can tell you from my own personal experience, learning how to wire makes a profound difference in what you can do.

John

Thank You John!  You're exactly right.  I've watched Boon's wiring dvd at least 10 times since I got them in May.  I had to re-wire sev. trees that were just awful after seeing how it's supposed to be done.  So at least I've learned now, after doing it wrong for so long, the proper technique; it's just that I'm still not good at it

I think I may still contact Matt as having one look at you wire, and the final wiring job, is invaluable.  The workshops I've attended, which is many, it's always a tree demonstration, or one where you make a bonsai from given material.  Wiring is never been emphasized.  Only now am I realizing it makes a big difference, and esp. challenging on easy to break branches like the BC.

mcpesq817, I basically am starting over on this tree as the branch ramifications were just not good.  I have noticed the strong apical growth and I'll keep a keen eye on the wiring when I get to that point.  Right now, i'm just regrowing new branches and pinching them for better ramification (Thanks to Don Blackman for this technique). 
Funny thing you mentioned the upward, almost straight up growth of some of the new growth.  They are great when you are working to extend the apex, or wanting a taller tree.  But I agree, they seem to be more prevalent in BC's than other trees I've worked on.  (I'm leaving them on right now as I'm attempting for the first time to do an air layer on one of the roots for a better nebari.  Though I'm not sure it'll help or not)

Thank You Guys for the help and inspiration!  Greatly appreciated!

Brent at www.evergreengardenworks.com has BC seedlings, but the size he has available right now are probably half the width you are looking for.  But they do grow fast, and you can't beat his prices.

He may have some larger stuff not listed in the catalog, you can send him an email with what you are looking for.

- bob