24-28 weeks for gestational diabetes test. The ultrasound thing depends on your doctor. Most doctors only do 2-3 ultrasound in your entire pregnancy unless there's something wrong. But they will take a urine sample and check your pulse and blood pressure and they check the heart beat. It's just a Doppler on your tummy with some gel.
At my second appointment they took my vitals, urine sample, listened to baby's heartbeat, asked about genetic testing (if we were getting it done or not), and then asked how I was feeling, and covered any concerns.