How early should I go for an ultrasound ?

I’m 4 weeks 2 days. I want to announce to my family at Christmas (I will be 8 weeks) and I’m wanting to give them an early ultrasound. My doctor can’t get me in until January 17th where I will be 12 weeks already. I really want to go a little earlier for peace of mind and to have an ultrasound to announce with. How early should I go? Any ideas on where I could go or how I could get one done?