Even before the music (and the media WAS bad back then too,BTW)grew really Woodstock bad,the "comedians" and even some of the songs,were ridiculing parents and calling for rebellion."TICKY TACKY HOUSES" is an example.
None of the "free love",dope,feminist junk,and use of bad words were "new",but suddenly this stuff was no longer fringe;as it had been for 100s of years.And 1968 WAS the pivotal year.
They were "jockying for position" and "locking and loading" for years, that's true. In '67-68 was when they struck with their full fury.
They had laid groundwork for at least a decade before, if not longer. All they needed was the right combination of events and demographics. Communists, over the decades, have shown amazing patience in carrying out their plans.