well, there're plenty of things affect the answer for this question that it's all up to you to decide now. Laptops aren't something people normally give out on christmas so take regardless it's before or after, the market price won't be too much different. If you wait for after christmas then there'll be another million people in school, not enough money waiting for buy at that time, too. (by the way, it's reasonable to get the laptop when school starts than to get the laptop during 1st-and 2nd semester break since if you wait that long, then you probably just don't need the laptop at all. Before school start and after school start --> nah, that's wrong, what make it cheap probably is those big saving coupon before school start a few years ago, nowaday, Dell gave it a "good bye" by giving out coupons every month (if you watch closely like I do, regardless I do hate Dell a lot). The only thing make their coupons different from each others is by giving them out publicly or secretly.
Take this as an advice: Nowaday, sellers are smart and so do buyers. --> everything will be at the market price no matter what day you buy stuffs (things with value > 200 in general).