New Mommy

I also had to wait until 8 weeks to get my first u/s. It's because of the way an embryo develops - this is when it stars to have a head and body. They can take measurements and estimate the due date based on them. I actually came back due a few days earlier than we initially thought which was nice - the sooner the better :)

I would suggest picking up the Mayo Clinic Guide to a Healthy Pregnancy - it's an excellent reference and very calming and helpful.

Good luck!

Christine