I recently read you can tell by your first ultrasound. if the placenta is on the left it's 90% a girl and right it's a boy. but remember the pictures are flipped when printed. THIS IS JUST A FUN THEORY that's being studied atm. but if you're baby is in the right position at 13 wks they can usually tell. most gender tests are between 18-20 wks
my sister found out at 14 weeks.. just depends on your ultrasound tech or if you get a blood test early saying what the gender is.
with my son he was so proud to be a boy... I found out at 16 1/2 weeks. but all babies are different