I don't have much cycling specific gear.
Last winter, I rode down to 0 F. I wore long underwear, wool socks, Carhartt work pants, Hermon Survivor steel toe shoes (required for work). On top I wore long underwear, t shirt, BDU shirt, a L.L. Bean windbreaker. I taped up the vents on my helmet. On my hands I wore either ski gloves or snowmobile mittens, depending on the temperature. I wore the mittens when it was colder. I also wore a chill choker or a balaclava as required with 180's ear muffs.
The only thing I am planning on changing is the windbreaker and the footwear. I am swapping out the Hermons for L.L. Bean snow sneakers. I am swapping out the windbreaker for a J&G jacket.
My normal commute is 6 miles one way.
I am not sure how much longer it takes to get dressed for the ride. I do know that it takes me longer to actually get to work, roughly 15 minutes or so.