WAY TO GO, katluvr! It's such a big deal to take that first step. You'll totally figure out the change of clothes and hair, just try different things and you'll find what works best for you. I started on casual days like you, and then on another non-meeting but not casual day took the next step, and so on. If you have a place to leave a set of clothes I found that made it really easy -- I knew I had to drive some days, so brought the clothes to the office for the bike days. Some people have a whole extra set of hair stuff (dryer, gel, whatever) at the office...experiment!
As for some of you other hardy souls, keep it going! I'm kind of bummed that I decided to telecommute when we were due to have negative temps with major windchill on top of packed snow/ice last week. My record is 9F, and I haven't tackled more than an inch or so of fresh powder before. I did break out the studded tires though later in the week and felt awesome, so now I know I can do that part. And I'm certain I have the clothes gear to be happy around zero...I think I'll get my chance again before the end of this winter.
As for this week, 0 for 1 so far. My commuter is in pieces in the other room. My overhaul got interrupted by house problems...better get in my work clothes and figure out what I need from the LBS tomorrow!
Sit bones = ~135 mm, saddles that work ~ 155cm/6.1 in wide
2003 da Vinci (custom road/all-rounder)/Terry Butterfly Ti
1994 Gary Fisher Nirvana (vintage MTB/commuter)/Terry Butterfly Chromoly
1991 Terry Symmetry (NOS frame/fork, project in progress)
1973 Raleigh Super Course (project in progress)