So at my last doctors appointment she said I get to find out the gender next time I come. She wanted my to book it for 3 weeks instead of my normal 4. My husband had to go out of town for work on the 3 week so we had to book for 4 weeks out so he could come with me. She wasn't happy about it and said she doesn't like to do the gender ultrasound that late. I'll be 20 weeks 5 days. Of course didn't ask her why so now I'm wondering do you have only a small period of time to do it? I'm confused on why it would matter. I would think the later the more accurate it would be.