… And so, 'next Monday’ typically means ‘this Monday.’ If you wanted to say “next Monday” as I mean it, you’d have to say “the following Monday,” pretending not to care that “next” means “the following.” We are burdened by societies’ inability to differentiate “this” and “next.” But if you really want to prevent confusion, just say “the following Monday, the ninth.” In this case, proximity and day of week are relevant, and we forget the number.