She didn't want her friends to view her profile and see "It's Complicated," so she made sure that you were a serious item before the official announcement. Now that your relationship has popped up on everyone's newsfeed, you need to allow for the all of the unnecessary excitement to simmer down. Wait until the notifications have made their way off of everyone's homepage before you break the news to her. You don't want to piss her off when she's active online. It will only take her a few minutes to create a "Dudes Be Like" meme with your photo.
The Day She Changes Her Relationship Status on Facebook