TinCow, you presumably would know the details if you yourself had a role to block (or over-write), right? I would not expect you to lie to protect that information unless you were very sure of the implications as they would impact YLC, and you don't seem to be.

In any case, being used to CFC and a whole lot of items in my "mafia" games, I would call it not at all unlikely that items' effects are only forward-looking: if something arrives by PM at the morning of day 5, it starts its effect then, regardless of having been "sent" the evening of day 4.