Is it okay to BD before U/S?

I'm getting an ultrasound tomorrow to check if my follicles are mature/big enough. If they are I'm getting a trigger shot. So excited! Is it okay to BD tonight, less than 12 hours before I get this transl u/s? Will it mess up the ultrasound? I just want to cover all my bases. I know I'm probably just being paranoid, but I've waited a while for this and I really don't want to mess it up! Oh and I forget off the top of my head, but how long after the trigger shot do you ovulate?? Thanks all for your answers!! :o)