I was 37 weeks because my daughter was in the wrong position to tell at the 20 week ultrasound. XD Generally they'll tell you at your 20 weeks ultrasound since the baby is too small to tell for sure before then. Like someone else said, certain blood tests can tell you earlier but they're not tests everyone gets. That kind of blood test is usually checking for defects or disorders that you're at risk of passing on to your child, especially ones that affect only one gender, so they specifically check it. I wish we could all find out from a routine blood test at 12 weeks! Lol
16 weeks with 3D ultrasound
19 weeks via ultrasound:)
15 weeks 2 days with a 3D ultrasound
15 weeks via 3D/4D ultrasound. You can buy sneak peak on amazon for $100. It's a blood test that can tell you starting at 9 weeks.
Found out at 13 weeks by ultrasound and layer confirmed with a blood test