Similar for me to t b known's comment above. I count from when I was born in, the indoctrination starts then. And I count to the night I walked out of the Kingdom Hall, looked back and said to myself " I'm never going there again".
I had been mentally out for a couple of years, and inactive for well over a year at the time.
It is an interesting question to pose, as many may be honest enough to count the time they were still mentally entrapped by at least some of the JW beliefs even after they had physically left. Considering it for myself, when I left I no longer believed in any of the Unique teachings of the J.W.s, just some of the beliefs common to all Christian Sects, of course, they have long gone now too!
I am now a Happy Humanist Atheist.