13-14 week gender ultrasound?

I am wanting to get an early gender scan, I know it’s possible to get it done from 14 weeks, lots of places around say from that date, but due to mine and hubbys work schedule, the only time we’d be able to come in is when I’m about 13w4d. And they offered for me to come in at that time.

Do you think it would be accurate? They do have a guarantee from 14 weeks, but I’m wondering if 3 days can make that much of a difference?

I’m super keen to find out, but also don’t want to waste my money if it’s too early!