I can recall a number of "moments," all of which happened right in Bethel (France). None of them were exactly about the WTS being wrong though -- I guess I had all the elements to realise that for some time, what was lacking was a good reason to admit it to myself.
I had been having a lot of deep conversations with a few friends. Especially one "sister," a DO's daughter, who had been working there with her husband for some time; we understood each other as neither of us had ever been understood. And she was leaving Bethel very soon.
I remember one day, while I left my room, I was struck with the certainty that my life would never be the same again. I was not afraid, just plainly desperate about the grey, dull, uninteresting days to come, and it was a choking, unbearable feeling. As I was descending the Bethel stairs, a pretty odd idea hit me. Instead of living my life and planning for the future I would henceforth be watching at it, minute by minute, with only mild curiosity of what would happen to me as if it happened to someone else. This was possible. I leaped through the last steps and reached the ground floor with a strange lightness of heart.
A few weeks later, I took a pause in my office to read a page of the New Testament (I was then reading it all again in the original Greek, and it was fascinating). I had reached chapter 8 of Romans, and read it as I had never read it before -- taking it naturally to myself instead of some special "anointed" class. I was breathless, crying of joy at what I was reading -- even before I realised I was putting myself in serious trouble.
A few days later, my mother (who was never a Witness) called me in the office. She was moving to a smaller flat and asked me what she would do with a few things I had left in her home. To my own surprise I found myself replying that I would take care of it. As soon as I hung up the phone I started to write my resignation letter, without having planned it before.
I have found that very often, the most serious decisions are secretly prepared in the depth of our soul and reach consciousness in the most casual way, overtaking our self-defence strategies by surprise.
This reminds me of a case I read some time ago on a French-speaking forum: a (now ex-)JW was preaching from door to door with an elder. At some point the householder asks him: "Do you really believe that?" He looks at him, says "no" and walks away never to come back, leaving the dismayed elder and the householder there. Funny, and so true.