Firstly, welcome!
You and I are similar in that we have both discovered being transgender only a few months ago. I've started T three weeks ago tomorrow.
Secondly, never assume you are indispensible. No matter how good you or your management appear to think you are, there's is always something that can trigger you being disposable and replaceable.
Thirdly, Dena has made important points.
Fourthly, while I am in corporate environment I'm not under lock and key in a cage where I just generate bits and bytes through my keyboard
I've worked in my job quite a long time and there are many dozens of people who know me as female right across all branches of the corporation. Sure there is HR who can be engaged to do some diversity training and do the explaining about what diversity means and enforce corporate diversity policies and support for people whatever diversity spectrum they sit on. In practice, I am still clearly holding the responsibility for coming out to all my colleagues that I interact with daily or less frequently.
I'm not yet out, because, as Dena said, it can take quite some time before changes become noticeable. It is a transition, not a sudden quantum jump from female to male.
I've decided to go by feel before I talk to HR first and then my managers ( email will be better because it gives me time what I need to say and explain briefly; I'm not great at talking face to face). When will I do that? Well, I will take cues from changes actually likely to be perceived.
My voice will be the first to change, but even that will take some time to stabilize and in that time it can be interpreted as just having a cold and being hoarse for whatever reason. This will not trigger anything for the next few months. If however, my voice drops to a very low level where it cannot be interpreted as having a perpetual head cold, this will trigger contacting my managers and HR.
No other physical changes would be noticed by anyone other than my voice ( unless I suddenly start going bald in a bad way). Facial hair growth is not likely to make a big appearance for quite some time, but should I be so lucky, then I'll just shave away the evidence until I'm ready for it.
I've always dressed in a way that was more male or androgynous, which means that nothing will change in that regard and nobody will notice. They sure as hell would notice if I suddenly appeared in a dress or skirt!
Perish the thought!
It is definitely not a clear cut case of going away for a few months and return as male, because there is just no way of knowing how long it will take before you can pass as a male. Most likely it will take about a year before you pass ( less if you are lucky).
Sorry for the muddy waters
