I worked from home 3 days a week when I was pregnant with LO 2 so I just told my boss in person.
I WFM FT now and rarely go to the office. I am going in next week for a meeting but I think 9ish weeks might be too early to tell him but it will be the only in person opportunity that I will have for some time. I don't have a desk or work space at the office anymore so I can't just drop by when I want!
Did you tell your boss in person, email or by a phone call?