4D ultrasound?

Des • US traveler. OR living. RH Neg life yo.
We are really anxious to find out gender, we're going in for an ultrasound this Saturday. I will be 15 weeks and 6 days. Before anyone has anything bad to say about over doing ultrasounds, I talked with my doctor about it and it is totally fine. Has anyone found out gender this early? Has anyone had a 4D this early? What should I expect?