Marx's ideas came to impact society most directly after the Bolshevik Revolution of 1917 in Russia.
Karl Marx had written his books around 50 or 60 years before the Bolshevik Revolution. Of course, the books had impacted some people, making them think about how to reform their societies. However, no society actually came to be run (or at least to say it was run) on Marxist principles until the Soviet Union was created after the Bolshevik Revolution.
After the USSR came into being, Marxist ideas came to impact many other societies. The countries of Eastern Europe became communist. So did China, North Korea, and eventually Vietnam. These societies were, therefore, directly impacted by Marx's ideas.
So you can accurately say that Marx's ideas came to directly impact society through the Bolshevik Revolution, the creation of the Soviet Union, and the post-WWII spread of communism.