So, I know this wasn't really a philosophical thread, but in trying to answer the question, it occurred to me that I wasn't sure what I meant, in my own head, by "transition." I know we typically think of "transition" to mean, "get to the place where we blend seamlessly with the Cis world." However, many people here, including me, realized early on that we would never blend seamlessly with the Cis world. So, if that is not the end goal, what am I transitioning TO? I hear others talk about, "Living Authentically" but I think I have lived at least semi-authentically since I realized my gender at 6. Did I look like the other girls? No. Did others treat me like the other girls? No. But until I got to college, I literally had no idea that there were any options at all. (Which is part of why I am SOOOOO impressed with those who found a way in the 70s and 80s.)
So, was I "transitioned" at 6, when I knew who I was?
Or how about at 7th grade, when I started shaving my legs?
Or, high school when I started presenting female sometimes, and male other times? (I would argue that I don't have to be 100% either one of those to be "transitioned" since even cis women sometimes don't present as female 100% of the time.)
Or, the nearly 30 years I have not gone outside without at least mascara on?
Or, the nearly 30 years I have been on some form of HRT?
Or, the nearly 30 years since I bought or owned "boy" clothes? (With the exception that I did buy a man's sport coat for my daughter's wedding 8 or 9 years ago.

Except for that sport coat, I literally can't remember the last boy clothes I bought.)
Or, must I have medically transitioned? And, if so, how far? Is GCS enough? Maybe FFS? BA? (OK. I would really like BA surgery but haven't done that...)
So, when we say, "knew we had to transition" I wonder what we were thinking? There are days when I think I have "transitioned" already, and days when I think, "No, I have much farther to go."
Now, having written this post, I think I have an answer to the question of the first thing I did when I realized I had to transition (whatever the heck that means):
I took the next step forward towards a goal which remains undefined and probably always will be for me...
Kate