Two weeks is what it is supposed to be (exactly as promised). I can only speculate that the reasoning behind this waiting period is an attempt to prevent people from abusing the system by "instantly printing the money" so to speak (or at least coupons) without actually staying at Hiltons. Not sure if they achieved this goal, because one can make a reservation 4 weeks in advance, get the coupon in 2 weeks, and cancel the reservation.