when to do first check up

Hi all. I want to know when is the right time to do my 1st check up. My last period is on the 25th may and on the 1st July, I used the clear blue digital pregnancy test kit and I saw I am pregnant for 1-2 weeks. I went to a clinic today and did ultrasound but couldn't see anything. Is it too early for an ultrasound? Should I fast before ultrasound? Please clarify. Thank you