Finding out sex in very early pregnancy - has anyone done it?

[LewishamMum]

I'm just over 7 weeks pregnant with DC2. Have DD. Genuinely don't mind if DC2 a boy or girl, just incredibly impatient and nosy! Think maybe a boy just because my pregnancy so far is totally different and a lot easier than last time.
There are companies which send you home kits to test your urine and/or blood to check testosterone levels, during early pregnancy, which apparently give a very reliable indicator very early on about sex.
Has anyone any experience of this? Any recommendations on particular companies and so on? And was it accurate?!

@LewishamMum I had the sneak peek but I didn't do it at home, I went to a clinic and had a blood test at one of their sites, so it has 99.6% accuracy. I had this at 9 weeks. I had a mmc in my first pregnancy and I hated that I never knew the sex of the baby so I wanted to be able to give the baby an identity. It was of course accurate and that baby is my now 9 month old daughter.

This has all been helpful thanks. I'll wait till the 12 week scan, but last time though I begged and begged and it was 13 weeks, they just insisted it was impossible to say until at least 16 weeks.