Guess tomorrow works just as well, as 667 encapsulates 666, and "They thought it was coming yesterday" is workable with the "23 P@in" drop.
Tomorrow is 3:23am on Qclock. A day after "322" Skull & Bones? "Dual 23's" or "23" and the (3) "!!!" exclamation points—a type of "11:11" even.
And a pen from same day could be argued to mirror reflect [23] on the [55] to [25] axis. It's a strange pen full of nuance in anon's opinion (old 4th graphic related), so I dunno, and could be other pen(s).