“If its moitzie shabbos for you , you say good woch, if it’s shabbos for you you say good shabbos”
I think it’s the other way around: The fellow going home from an earlier maariv should say to the one who is going to shul “have a good Shabbos” since it’s still Shabbos for him. On the other hand, this fellow who is going to shul to maariv, should wish the fellow who is going home “have a good week” since Shabbos is over for him.