I was told they check as early as 17 weeks but it can be inaccurate with an ultrasound and waiting till 20 weeks gives you a more accurate result. I was 20 weeks when I got mine and ultrasound showed i was having a boy and now I'm 32 weeks and never been told otherwise and I ask about gender whenever I get an ultrasound because my boyfriend and I started buying boy stuff when we initially found out the gender. So 20 weeks was very accurate for me i know for a friend of mine at 20 weeks they said she was having a girl and a later ultrasound revealed she was having a boy. For most women the 20 week point is most accurate it also depends on how well your baby cooperates in the ultra sound. My baby didn't want to be in the right angle to see his gender it took us like 10-20 mins to figure it out he was being so stubborn.
I was 15 weeks with my first ultrasound and they said it was to early to tell so I think it's 20 waiting till 20 is best anyway really cuz they can find it very difficult to make it out, they told me 70% boy at 21 weeks, just hope it is a boy now
I was 18w6d when I found out
You can get sneak peak on amazon for 100$. It a blood test you can do starting at 9 weeks. You can do 3D/4D ultrasounds out of your own pocket starting at 14 weeks ( I did at 15 and it's very accurate and was very clear.) Otherwise your Dr will likely tell you at your 20 week anatomy scan.
I will be 15 weeks Thursday and I'm hoping they can tell me Saturday at my appointment at firs peek I paid 59 for it I get 2D/3D