Depends... I started off commuting in my work clothes (khaki slacks or Dockers, nice shirt, occasionally jeans), but then June arrived and Humidity with it... so now I pack a change of clothes in my pannier, and wear baggy shorts and a hi-vis jersey while out on the bike. I keep a suit and a "nicer" change in the cube locker for when I have to sit in on an unscheduled meeting with folk sfrom outside the agency.
I shower first thing in the morning, and once I get here, turn up the computer and run thru the night's e-mail while I cool down. A quick wipedown with a towel and Wet-Wipes, change into clean clothes, and I'm ready for the day. Afternoon is sort of the reverse, I change back into my bike stuff, pack up my work clothes to haul home for the laundry, and pedal away.