OK now let's try to have some fun and tie this together. What would Freud have said about Marx (I don't believe Freud ever analyzed him)?
Marx, from what I've read, was not a very cuddly character. He was always arguing with everyone (certainly with anyone who disagreed with him). He even had a contentious relationship with Engels who helped support him (constantly sending him carping letters asking for money). Not too nice as a family man either or so I believe. So for you Freudians out there was Marx a supreme egotist, one who so believed in the correctness of his theories that self-doubt never crept into his consciousness and what does that say about his thinking process. To the contrary, were his dogged, stubborn, self-absorbed efforts the hallmark of genius (regardless of whether his theories proved correct). In some perverse way he could be viewed as a romantic, the starving artist in the garret who sacrifices everything to feed his obsession. Likewise, another towering figure on the mid-19th Century, Wagner, also exhibited some of the same character traits. Marx's attempts to create a single unified economic theory with all the answers reminds me of Einstein's efforts with respect to general relativity and his effort to create the unified field theory and Emil Durkheim (April 15, 1858 – November 15, 1917) who together with Marx and Max Weber is credited with being the principle architect of modern social science who believed that "... sociology would not only discover "apparent" laws, but would be able to discover the inherent nature of society" (cf., Wikipedia). Again, I find this a 19th Century weltanschauung, the confident thought that everything, including society, could be reduced to a set of unified principles that answered all and that can be grasped by mankind. The end of the 20th Century, on the other hand, seems to me to have introduced an element of doubt, cynicism and introversion, creating greater interest in the self and perhaps the thought that life was not as simple as one would like. The Heisenberg uncertainty principle and the reaction to the horrors perpetrated during the last Century by followers of Marx (a somewhat eclectic and nonlinear holistic thought) strike me as examples of where modern thought has also gone. Is the battle between religion and secularism we now see (viz., the Taliban) a manifestation of these two conflicting world views? Is "Big Government" vs. the "Tea Party" (i.e., the state versus the individual) the opposite poles of the sole political choices available to us or merely evidence of a loss of faith in the power of institutions to solve all ills? Is the Big Bang evidence of the starting point of a scientific explanation for "everything" or does it confirm the Thomistic belief in the need for a "Prima Causa".
I'm afraid I have drifted from the original question of when did the Revolution start, unless one believes that the Revolution was an expression or culmination of an egotistical 19th Century world view that mankind has all the answers and can create heaven on earth simply by the proper application of certain "scientific" principles disregarding the inherent fallibility of mankind.