We all have our unique circomstances but I started my transition on the job (as an executive manager in a medium sized international business) believing I had the full support of my boss, the CEO of the company. Even now, I believe he was sincere at the time (last July).
However, no matter how much official support you have one thing you have little control over is how other people react. Actually I think the real issue is that most people actually have little control over how they react either. Conciously they may be telling themselves one thing but unconsciously their brain is telling them something very different ie. most people who practise discrimination are in total denial on the subject, especially well educated people who think they are completely above it all. The Americains here are probably familiar with the line from the book, To Kill a Mocking Bird, which sums it up so well "People generally see what they look for, and hear what they listen for..."
Anyway, immediately following the green light from my boss, I came out one to one to all of my colleagues on the company management team, all males bar one, getting mostly neutral reactions. Just one person told me outright that he thought he would never be able to see me as a woman.
As my company wanted me to have my Civil Identity Change done and dusted before coming out officially and transitioning on the job, I filed for the change last Sept, continuing to present as a very androgenous male through to the end of the year. The public prosecutor gave the green light for the change last Nov but since then, the court has repeatedly failed to set a date for the final hearing so I still have no idea when it will finally come through.
Meanwhile, life in the company continued but I noticed a real degradation in my relationships with my colleagues on the Management Team from Sept onwards (not anyone else though) , to the extent that by the end of the year, it was getting increasingly difficult to function properly in an already very demanding environment.
I could see all of this happening and suggested to my boss that we bring in a mediator to get to the heart of what was going on. He unfortunately refused , considering that any problems encountered were for me to resolve. So without specific action to try sort out the issues, things just continued to get worse until I was told a few weeks ago that my mission would come to an end in July once my fixed term contract comes to an end. (N.B. It had always been understood that this fixed term contract would eventually become an open ended contract)
I took a very hard hit at the time as I had put everything into this job but have recovered quite a bit since and am now turning my attention to creating my own business, hopefully with my present employers as my first customers.
On the positive side, I finally transitioned on the job without my CIC as I was male failing far too often, creating awkward situations for everyone concerned . I also basically said to myself that I may as well be hanged for a sheep as a lamb so, with little left to lose, I forced the issue a bit.

To the credit of my employers, my bio on the corporate web site, including my photo, is now 100% feminized and after about 3 months to get used to the change, even the slowest of my colleagues is now on board, at least regarding the use of my name...
More than anything, in this pretty painful and potentially dramatic situation (I'm also getting a bit old.. ) , I remembered some stuff I had taken on board(from Tony Robbins) a few years ago when I was working as a business coach. Life doesn't always work out the way we want ie. according to our blueprint. In such situations, to get your life back on track you have two choices, change your environment or change the blueprint. I don't have the power to change my environment so rather than fighting against windmills, I think it is wiser to change the blueprint, taking as many positives as I can from my existing circomstances ie. creat my own business with the support of my present employers whom, after a bit of a crisis, I will finally most likely quit on fairly good terms.
For those facing similar situations, I found a fairly good article on the web which goes through the thinking
http://sourcesofinsight.com/tony-robbins-on-what-to-do-when-life-doesnt-work-out-like-you-planned/Hugs and best of luck to all of you!
Donna