Girls good day, on what day can you already do an ultrasound and go fo…

Girls good day, on what day can you already do an ultrasound and go for an appointment? Today I was at the appointment and they didn't look at me and an ultrasound wasn't done) And they said that the pregnancy test is not indicative! What is this even about? Today I did a test in the morning and it showed a second line, up to the delay of 3 days.