For a quick reference, booked 3 certs out of my stay and exactly at 72 hrs before check in, at 15:00 sharp -- which is 25 minutes ago --received email that I have been upgraded.

checked app, was upgraded from resort view standard room to ocean view standard room (1 category upgrade). So it's an automatic thing, and very standard. I'd expect every diamond receiving exactly same upgrade from this automatic upgrade mechanism.