I've had six rentals within the promo window and all of them have been corrected for the 2x and 3x points. Interestingly they included bonus points for a rental I picked up on May 1st, but didn't register until May 2nd. So Hertz is using the return date for the promo start and not pick-up date.
Also they used my most recent rental as the 2x one which worked out in my favor.