Re: I know the standard time to tell people you're pregnant is 12 weeks, but I really just want to let the cat out of the bag! Is it incredibly irresponsible of me to tell just about everyone I encounter as soon as I know?
Personally, I'm not embarrassed to share anything that happens in my life with anyone, and miscarriage—the threat of which causes many women to wait to spill the beans—is a heck of a lot more common than most of us girls know. Just bring it up with friends and you'll be surprised at how many of them will confide that they've had one, or more.
Do what feels right for you, but if you can stomach it, tell at least one mommy girlfriend you are pregnant so that you can complain, wonder, rant, and marvel to someone who can truly empathize.
Also, think carefully about how and when you want to break the news to your boss and coworkers before you let the status slip at the water cooler.