Ultrasound/finding out gender

I will be 10 1/2 weeks Thursday which is my first appointment, finally! The doctor was booked and it took me 2 1/2 weeks to get in.

From past experiences with my doctor you see him and then make an appointment for an ultrasound and an appointment to see him again in 4 weeks. I am nervous that I am going to have to wait another 2-3 weeks for my ultrasound sound. At that point I will be almost 13-14weeks. If I do have to wait that long I might as well wait until I can find out the gender. How early can they tell you the gender with an ordinary ultrasound?