As soon as i get a chance i will take you on in one, then you can see how
   

To answer your guestion, your car rank pointsdetermines if it does it instantly. For example, if your mustang is ranked at #50 and you want to face off with someone who is at #30 you have less car rank points and the JFO is put on right away. If you are at #50 and want to face off with #100 they will have to accept your challenge before the JFO is started. I think if you have more than 500 pts than them they have to accept 1st, and if you have less than them there is no acceptance.  If I were to challenge onebad95 (and he had the FO option on) it would be put on right away. When I challenged crimsonblack, he had to accept first. Does that help?

Yes it does. 

Thanks YS