I think It's acceptable to say, on Sunday Sept 4, "We're going to do _____ on Monday" - having the same meaning as "tomorrow"
At the point of Sept 4, I'd say "Monday" = "this Monday" = "tomorrow, Sept 5"...... whereas "next Monday" is more ambiguous but could be assumed to mean Sept 12.
If we're discussing dates on Sept 3, on the other hand..... if someone says "next Monday" I find that almost completely ambiguous
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bokonon get your sense-making the **** out of this topic now - Cat1001
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