I read a JW-expose' book in Dec. 1987 and told my wife a month later I didn't believe it was the "Truth" any longer- sent my exit letter about 4 months later- got my divorce papers a year later from my JW wife .
Now the big one was when I stopped believing that Jesus was the truth in 1996. It took me four years to admit to that one publicly. I converted to Judaism in 2001- nobody ever asks what I think about Jesus now.
shalom,
Moshe