Sometime most of the students preparing for JEE give SAT. But they get worlds some top university like Harvard, MIT, Cal tech, etc not IIT. I would say that SAT and JEE are totally different. SAT is more based aptitude. So most of the smart students clear this exam without much hard work. Where in terms of JEE you need hard + smart work. So, just try to master the JEE Advanced exam and give SAT too. SAT preparation will be easier once you are done with JEE advanced.
Hope this helps!