I would say you get the best pictures at 16-24 weeks. Some people, I've heard, have gone in for gender confirmations at 12 weeks but I dont think those 3D pictures are as clear as when the baby is older and more devloped.
I waited till I was like 32 weeks because I wanted to see my baby full grown just about. But if you're looking to see the gender 16 to 20 weeks is good. I also got my babies heart beat in a cute little monkey stuffed animal.
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