By the early 1870s a loose group of Paris painters, Monet, Renoir, Degas, Pissarro, Morisot, Sisley, Cézanne, were tired of being rejected by the official Salon. So they staged their own show in 1874.
A guild before it was a movement
Before the 1874 show, this group was a creative community first and a movement second. They met at Café Guerbois and later Café de la Nouvelle-Athènes. They argued about color theory, plein-air practice, modern life as a subject and each other's work.
What we can learn
The Impressionists did not wait for permission from existing institutions. They built a small, local, conversation-driven room and turned it into a movement. Every creative scene worth admiring has worked roughly the same way.