How early can you find out the gender with ultrasound?

Nathali • Married ♥️ Mommy of 4 boys! 🧑🏽‍🦱🧑🏽 👶🏽👶🏽

I keep seeing post of people finding out as early as 12 weeks saying it was an ultrasound and other being tested I was told I had to wait till 18-20 weeks but today my doctor said we can probably find out tomorrow at my appointment. I’m barely going to be 13 weeks on Wednesday.