12 is an automatic winner.

[Automatic Monkey]

Can we?

Just sounded like to me one must redeem the first 2-card 12 dealt after informing casino that you have the coupon.

I guess it might be a different story if you could use the coupon whenever you chose to after the fact of knowing the dealer's total for his 2 cards.

I don't know the exact rules of the coupon.

Yes, the precise rules of any promotion are important. Two promos can sound almost exactly the same but be subtly different in a way that alters how they should be played. Because the differences can be so subtle that the casino didn't take them into account, there can be hidden EV there.

With this coupon, instinctively I would whip it out in a slightly negative count, but not so negative that I would otherwise leave the table. It might not exactly maximize the value of the coupon, but it would maximize the value of my time in the casino with the coupon.