[Ref in PA]

4-41 defines when a try starts and when it ends. As part of the rule, the "act of shooting" is defined. Article 3 says it best: "The try starts when the player begins the motion which habitually precedes the release of the ball."

If fouled after that motion starts (certainly being in the air for a jump shot qualifies) then free throws will be shot, even if the ball is not release after the foul. The ref is the judge if the try was started or not. So, don't ever listen to a player about if the try was started or not.