It might be a little early, normally they try to wait until the 20 week mark. I had mine at 17 weeks 4 days and that was considered early. But you can always ask, all they can say is no. :)
They will do an anatomy check you'll be one day shy of 16w...tell the tech about your son...they will def pay special attention to the kidneys...they are usually really good about that kinda stuff