This is a great question, Moni!
My case might seem a little odd, but it is largely a product of my age and upbringing.  It was a two part process, recognizing my true nature, and deciding to transition.
I recognized my nature over 30 years ago.  The childhood 'cure' I had gotten was wearing off, but I didn't know what I was other than what I had been told, nothing good.  I was definitely in hiding, even from myself.  We were interviewing folks for a position on my engineering team, a rather grueling all-day interview process.  One of the candidates was a transwoman who, unfortunately by the end of the day, was showing a 5 O'clock shadow.  I remember sitting there talking with her about the opportunity and our needs, when the thought popped into my head that "She's so brave.  I wish I could do that."
Wait.  WHAT???   My sneaky subconscious had just outed me to myself.
Given my childhood rearing, shame and repression came easy to me, and I resolved not to hurt my wife and young children, and take this to the grave.  I almost made it.
In March 2016, just over a year ago, I planned to end things.  My mind was crumbling, my core being corroded away from repressing this.  I called a hotline in desperation, and was talked down and quickly placed in therapy.  I got treatment.  My spouse and I negotiated terms for what I could do.  They were restrictive, so restrictive that I broke down again in a few months.  I convinced her to let me try HRT.  I started seeing a gender therapist.  Finally, I reached the point where I knew I had to stop putting everyone else first and myself last, and had to take action.  My spouse told me this wasn't working for her, and I'd have to leave.  I resolved that if I wasn't living under the same roof as her I would immediately go full time and transition.
I did.  I moved out on October 22, 2016 and immediately went full-time.