Saturday.

I think there should be a special name for the first Saturday after you start back to work:
Maybe 'Ahhhhhhhhhh....-day.'
Maybe 'Scrub-your-knuckles-off-day'
Maybe 'Shamelessly-drink-an-entire-pot-of-coffee-while-still-wearing-yesterday's-mascara-day'
On second thought, maybe Saturday says it all.