So I've worked for this place for several years and am the senior dev (small place). I only just emailed him a few minutes ago to let him know I'm trans and will also be out for over a month in January - February for surgery.
Peak anxiety, man. AMA.
Edit: he's cool with it! He said he did pick up on some cues so...yeah! He offered to help tell my coworkers too, which is something I have to think about (but seriously awesome too). Looks like I'm keeping my job!