Insurance during pregnancy?

I just found out I am pregnant by the home pregnancy tests! Yay! I signed up to receive health insurance through my job, however, it does not go into effect until January 1st, 2013. I currently do not have health insurance right now. Can I wait to go for my first check up until January when my insurance kicks in? If I go to a doctor and pay cash like at a walk-in clinic or something, will my pregnancy be looked at as pre-existing when my insurance starts? Thank you for your help. This is my first pregnancy and I am really excited.