I know with BRU your event date is usually your due date when you register. The coupon will say that it is only good on things added prior to receiving coupon but I used to work at BRU and it would work on things even added the same day of you using the coupon. Of course we aren't supposed to tell people that but it does work, as long as it isn't one of the many items that are excluded. HTH :)
Edited to add.. with BRU your coupon SHOULD come anywhere between 2 to 4 weeks before the event date or up to 2 weeks after the event date. If you don't get it you should be able to call the store and they can give you a store issued one.