Hi Mark!
The Magic Bands are exciting, aren't they??
Unfortunately, I don't have any concrete details on the Magic Bands and when they will roll out to different resorts. However, they are scheduled to roll out through the rest of 2013. Hopefully this means you'll have them in December!
Typically, from what I have experienced, the customization option occurs around the time that online check-in opens.
You may also want to keep an eye on the
Disney Parks Blog.
They have released some details on the the entire My Disney Experience
and Magic Bands and I'm sure they'll be the first to have the scoop as
to their official launch date.
Sorry I couldn't have been more of a help!