Consensus for an unbelieving offspring, please

[LakeErieUmp]

My 14 year old son, as with most offspring, refuses to believe just about anything I tell him but he has agreed to listen to the consensus of this board. (By the way, he's a fairly decent and smart player - 10 Ks in four innings pitched Monday and is a solid catcher when not pitching, in other words, he knows his primary responsibility is to not let PU get hit!)

ANYWAY, he does not believe me when I tell him that he can immediately take off as a runner when a pitcher in the windup position moves anything. In other words, that F1 has only two options (other than stepping back from the rubber). F1 can step toward a base and throw to it otherwise once anything moves F1 can only deliver a pitch.

Frosty-glassed adult post-game beverages are on me for your responses.

Thanks!