baby announcements

Katelynn • 29, married, mom of 2 beautiful baby boys, one is a newborn and the other is 2 years old
I am so excited about my pregnancy and only found out Monday. I told my mom and husband right away. We are having my brothers and their wives and my parents over Friday to tell them. We got my 2 year old son a shirt with a dinosaur on it that says Raawwr means I'm the big brother in dinosaur. That's how we are tell the family. 
Other than that we are waiting until 12 weeks to announce. I'm not positive on my due date because I don't go to the doctor until the 18th, but I think I'm due about June 5th. That puts me at 12 weeks in December. I really want to do some kind of Christmas announcement.
Has anyone figured out how they plan to announce theirs?