To kick off the first day of Fashion Week, the Cut sent photographer Youngjun Koo to snap the most stylish of fashion world peacocks (off-duty models, editors, blah-gers, street-style royals, and more) finally given the freedom to show off their glorious feathers with abandon. But surprisingly, day one's theme was casual minimalism (for these people, at least). Plaid tops, monochromatic looks, and denim-on-denim outfits ruled the scene, along with a generous (and obligatory) sprinkle of little black crop tops. Subtle geometric prints blended into neutral-colored jackets, and buttery leather baseball caps have already claimed the title of "must-have Fashion Week accessory" — though David Yi's eye patch comes in at a close second. Click through the slideshow to see how the fashion elite transitions from summer to fall. You really don't want to miss Nicola Formichetti casually smoking a cigarette in a revealing mesh black top. Someone's not ready to kiss his hard-earned summer body good-bye.