Are you in charge of making the announcement? Cause if not... "That's just, like, your opinion man." .
Aw man. I thought I had a good quote there! Which was the only reason for the question sorry lol. Wasn't serious.
In this case, "a day" means a day sometime in the future not constricted by the human understanding of time or the need they have to constrain it's boundaries.
I think I smell what the Dreamcleaver is cookin'. Clearly, your misuse of "it's" as a possessive pronoun is a sign that we don't actually need to constrain time's boundaries...time is the boundary. By my calculations, that indicates the announcement will be Wednesday?
I feel cheated. I thought this was a riddle and I solved it! As a consolation prize, can you just go ahead and let us know what day?
So, not Monday, and now not Wednesday, but still this month. Saturday can likely be ruled out due to not posting on the weekends, but that is a LEAP of faith! That leaves Tuesday, Thursday, or Friday. Put me down for Thursday, because the god of thunder is a notable medieval meme and a good day for this lightning to strike!