You can do this! Make your plan and fully commit yourself to your transition, but know this: as you move through transition, there are always going to be people and circumstances that will surprise the dickens out of you.
I did transition on the job at a time when such things were very uncommon; generally speaking, people are much better informed about such matters these days. When I transitioned, I worked in a key management position of a small corporation; for 7 years, everyone had known me as a man. Before I made any big decisions, I made sure that I had the support of my bosses. (My direct boss did not agree with what I was doing, and we had long, heated debates on the subject, but he always supported my right to self-determination.)
In November of 1998 I attached a "coming out" letter to every paycheck of every person in the company (about 150 people). It was the day before Thanksgiving. The letter informed everyone that when I returned to work the following Monday, I would have a new name, a new look, and a new gender. The president of the company also attached a letter to everyone's paycheck letting them know that I had the full support of management and that no bigotry would be tolerated.
I pretty much knew which staff members would be supportive of me, and which ones would be hostile. Almost to the person, I had it completely wrong. The people I expected 100% support from turned completely hostile and distant, and the ones I expected rejection from became my most enthusiastic supporters/defenders.
We, none of us, know the future. Don't let your fear rule you. Keep a positive attitude as much as possible, be the kind of person that others enjoy being around, commit to your path, and stay flexible enough to let life lead while you follow.
I stayed on that job for 2 years post transition. Since then I've been in 3 significant relationships (I'm about to celebrate my 7th wedding anniversary.) Also, since I left that first job as Miharu 14 years ago, I've worked in the finance office for a chain of health clinics, I spent 4 years running the offices of a construction firm, I was a finance professional for V-Tec, then for Widmer Brothers Brewery, and have worked in my present job, the international headquarters for a large Catholic ministry, for the past 8 years. I've never lived under a bridge, never been homeless, never wondered where my next meal was coming from. In fact, since transition, I have enjoyed far more success and acceptance in the workplace than I ever experienced pre transition. If I had to pick 1 reason for that success, I would say it's because I've been a happier person. In my experience, when put in a pool of equally qualified candidates for a potential job, I have a tendency to stand out as the happy, friendly, positive minded individual in the crowd. I know for me, when I hire someone to work in my office, I always gravitate towards the person who I believe will be the most enjoyable to spend my days with. I believe a positive attitude has always given me an edge in business, in love and in life.
Sorry for the length of this. I had a lot to say. I hope you find this helpful.
Peace,
Miharu