Really dumb question, sorry: is rent for, say, June, due on June 1 or on May 1?
boy, is THAT a stupid way for someone to word that phrase: "in advance" AND "on the first of the month." No wonder you're confused.
I think I'd guess that June rent is due June 1--it's in advance for most of the month, and it is on the first of THE month, not the first of the PREVIOUS month.
Thank you. That was my guess too.