Do you really think DL (or for that fact, even you yourself) will book away from DL just because you don't get the DM benefits until March 1? I seriously doubt it and I am sure DL does too. They know they have you over a barrel with your anticipated DM benefits. No need to rush it from their perspective.
That is why DL gave you the drink coupons, for the times you don't get UG'd. It has been said that the coupons with the 12/31/09 expiration date are still being honored.
A NW FA refused to accept my 2009 drink ticket on 1/3/10.