This study, conducted by a British retailer, found that people spend dramatically less time dressing and grooming for work as the week progresses.
Gentlemen, society does not expect tremendously much of us in terms of prep time.
Shower - 10 minutes
Shave - 10 minutes
Brush your teeth - 2 minutes
Other ablutions - 8 minutes (I'm being generous here)
Put on a suit - 15 minutes from naked to dapper
We don't have to put on makeup, spend more than a minute or two on our hair, put on pantyhose, etc. Realistically, you're talking about 45 minutes alarm-to-door if you don't eat breakfast.
I keep harping on the idea that the way you present yourself is a highly communicative act whether you intend it to be. I harp because it's true. Even if you're hung over, come in Friday morning in a pressed shirt and pert collar with a clean shave and a little cologne. People notice even if they don't realize they notice, and you'll feel better, too.