I spent at least 30 years or more in denial, i.e. not even telling myself. Once I was done with that ("Yep, I'm trans. Now what?"), I knew had to tell my wife. The fear surrounding that was intense; it almost paralyzed me. From the time I decided I had to tell her until I actually did was probably something like six months.
Many, many times, I decided that it was time to tell her, yes, I'm going to do it. Any second now. Right now. Take a deep breath. Tongue starting to form the first worrd. And I would back out in a panic attack. That happened a lot over those months.
When I finally did it, I just kept telling myself over and over, "Gotta do it. Gotta do it." Finally, I dissociated and heard my own voice speaking the words I had rehearsed, thinking, "OMG, I am actually saying it!"
Once I was past that hurdle, the rest came easily. I told my neighbour an hour or two later, and then some email friends.
I still have fears about how I will be perceived in public when I am presenting, but I can do a pretty good "Damn the torpedoes" when I have to.