To get any rollover at all, you must earn more than 25,000 MQM in 2010, assuming that you start from zero, So, in that sense, any MQM that you credit will be wasted unless you cross the 25K threshold. Thus, your instinct is correct: there's probalby no reason to fly DL before 2011 starts (unless you value potential ungrades, etc. now). If elite status is valuable to you, additional months of it should be even more valuable for its inherent benefits, as opposed to whatever credits you get toward maintaining that status.