How early via ultrasound could you tell the gender!?

SO! I know most of the time we find out at the 20week anatomy scan what the gender of baby is, unless you do the blood test. BUT! My new OB doesn’t use a doppler on me during appointments, he has an ultrasound machine in the room & gives me little peaks & checks the heart rate that way. WELL! My next appointment I’ll be almost 17 weeks & was curious if there is a chance he’ll be able to tell me the gender at that appointment?! I have 2 girls already & this is my last baby (most likely) & idk how I feel about a boy or girl! I’m just so anxious. How early did you find out via ultrasound!?!? THANKS MAMAS (and daddies if you’re in here)