I told my boss & coworkers immediately. They had been there with me thru all of the infertility treatments (I'd had to take some time off for some of the treatments) so this was just the next step in a long line of steps DH & I had taken. At first, my coworkers asked a lot of questions but now they pretty much wait until I give them information. I do share alot!
If you are not ready to share this with your coworkers, then you shouldn't. If you were worried about the amount of travel that's involved, you could always go ahead & let you boss know so she/he would be forewarned but make it known you are not telling anyone yet so she/he won't let it slip.
When to tell people is a personal decision that should not be forced. Go at your own pace.
Good luck!
