Ok - this was a dilemma to me as well. When I was doing infertility treatments I had morning appointments, I work for a large company and had a very lenient boss so I did not have to tell every time I left for an appointment, but I told one person I trusted and when I left for appts. she would just say that I went to the doctor ...and then tell them to ask me directly ...no one had the guts to but they all suspected something.
Anyway - when we finally decided on adoption, it was a different story for me because it was more of a sure thing. So we just signed our papers in August, the agency has an average six month wait and then they do homestudy etc. and it's up for grabs from there. I was so tired of being secrective and I did just want to shout from the rooftops so I decided to share. We had a co-worker baby shower and I approached my co-worker and asked her permission to announce at her party - she was excited and more than supportive. There were about 15 + women there, when I announced it everyone was VERY excited and of course had tons of questions
I felt that it was the right move for me. I did not want to get close to the adoption date and then go "guess what"...I felt my co-workers would have been surprised and hurt, I felt if I announced it early that everyone could sort of build up excitement with me. Plus one of the women that was hosting the shower was adopted herself and everyone knew that so she was very supportive.
As for my direct boss, I told him the next day. Someone came up to me and mentioned it right in front of him. Honestly, I was not expecting much of a reaction either way...but it turns out he was excited for me...and he told me that he and his wife had looked into adoption because they had trouble with getting pg with their second child so he could relate. I have to say I was surprised and also relieved. Unfortunately for me right after I told him he left our company - so I will have to tell my new boss, but I have decided that I am just going to do it like and "fyi" because everyone else already knows.