I can’t say when except that I too have seen its use in writing explode in the last 3 months alone. Initially as “woo-woo”, abbreviated to “woo”.
From whence it comes? Here’s my best guess… I have no cite, but it’s a pretty damned good guess. In the early days of TV and cinema, the stock sound effect for a ghost was a slide whistle, which would sound a low, rising glissando vibrando as the ghost was rising up out of the grave (or whatever). Later, people would use a vocalization of that same sound for dramatic effect when telling a ghost story around the campfire (not a guess, you see this all the time, if you spend any time around kids and campfires). Over time, it was generalized to anything that was mindblowing or like, totally freaky, dude. Woo. You know?