First OB appt

I go on the 2nd. Originally my appointment was because I thought we couldn't conceive. But now (by the grace of God) I'm pregnant!! By time my appt comes I'll be around 8 weeks. Will I get an ultrasound then? Or no because my appt wasn't originally for being pregnant. I don't want to call and tell them I am pregnant because I'm scared they'll push the appt back (do you think I should call and let them know now, or wait until I go in). I guess I just need some advice. I can't call my mom because she doesn't know yet.. :(