Blood test for sex of baby

Amy Jo • 29, married to the love of my life, mommy to an amazing baby boy 8•11•15, now expecting #2 in April ❤️
Has anyone had the blood test done to find out what they are having early. My OB is old school and wants to wait till 20 weeks to find out via ultrasound. Where can you get this test done at? And how accurate is it?