Like most of these questions - it all depends! Actually, I work in tax and thats how I answer most questions I get!
Your work environment has a lot to do with the timing. I gave my work about 6 months notice all up but that was because nobody has transitioned on the job in anyone's memory and they do seem to like bureaucratic processes. I leave for FFS in 3.5 months and full time in January. My boss has been good about it and HR are involved. Another reason I have gone early with the notification is to allow my boss and HR to be ready if I am outed before full time. Boobs are the main concern. I have told them I won't be changing my appearance before January but HRT has its own timetable! I refuse to bind!
Where you work and the work situation around customers, team size, the sort of work come into play as well even if the concerns are unfounded. Remember you will be dealing with some people who have no clue about what being trans is about. I am a manager in our head office of an organisation that employes 2500 people and am the 2nd layer under the CFO who sits about 15 yards away! He hasn't been told yet but will soon. I only have 1 team member so the impact there is much more personal. I am going to be leading the disclosure to my team member and to my manager's teams personally. After that, it will be a blunt email after I go on leave.
If your employer is moderately responsible, it may have protections in the form of policies about these things. That may ease the process. If not or if they don't mention trans protections, then you may need to be prepared beforehand to be an educator especially around the legal protections in your state/country. New policies may have to be developed or old ones amended.
I have a couple of "no go" question areas (surgeries and family - HR have the view that even if I am off work for 6 weeks for FFS, we just say I am on leave) and these will be communicated to the immediate teams that report to my manager. I helped my HR by preparing a large information pack just in case they had no idea. That material is going to form the basis for an Intranet support page on trans issues as part of our Diversity initiative. The approach will be about accepting difference which takes to focus off me a bit. It will still be "Emma's page" to some extent!!!
As I wasn't aware of my manager's level of knowledge about trans issues (turns out he had no idea), I wrote a letter to him explaining what was happening and why. I sat in his office while he read it. His first response was "I much preferred to be reading this letter than to be you having to write it". He almost witnessed the first cry of my transition! He also made comments that while it was new to him, I had been living with this for so many years and that if all goes well, my transition at work will be all about me, not them. This may be "best case" wishful thinking! Our senior HR partner said that she couldn't imagine how difficult being trans must have been. I mention these comments as it gives an idea of the sort of organisation I am in.
A couple of final points. Grace is correct around confidence. My confidence is growing and the time feels right (that is, January, not tomorrow!). Self acceptance precedes this and is, in my view, an essential part. My work transition plan is mostly put together and I have made it clear that I am up for most things BUT I will veto anything suggested that I am not comfortable with. My position in the organisation might be helping here and also the fact that I am the first! They accept this. I have also said "no surprises" which they also agree with. Lastly, if you can develop allies (like HR and Diversity champions etc) before the wider disclosure, it will help both you and your boss.
Best of luck! Oh, and sorry for the long post.
Emma
PS I am glad I raised this with my work when I did. I have since changed one of my HRT meds and am way too emotional at the moment to deal with the stress of the initial disclosures. Just hope I get it under control before November!
