I think Art Deco was starting to emerge on Titanic. There are pit's and pieces. As for the full blown effect I'd say in the 1920's. The Great War slowed the movement down a bit but after the Art Deco movement came into full swing. Inger Sheil and Jason Schleisman, Jim Kalafus have a better grasp on this subject among others then I do. Hopefully they see this.