The1True
8, 8, I forget what is for
By setting a one-hour timer in full view of everybody, and secretly resolving that no matter what else happens, Vecna will arrive when the timer hits zero even if they're in the middle of another battle, I ensure that at least half of the time I have available for the game will be dedicated to the thing I meant to do (testing Vecna) instead of incidental details.
I'd be interested to hear how this goes...