No you don't... you just want it to stay away from the top 20% of the range. I ski 18 din bindings on 10 everyday.
(this is urban legend status) A LOOOOOOONG time ago, a few bindings had problems releasing right at their lowest settings, because things would not have enough tension on them, and slip out of place/seize/break you. BUT those problems have long since been fixed. Just make sure you get a release test done on them.
BTW, you suggested PX12s. the OP is light, so I think 1-2 pounds less for the Mojo bindings is much more important than the DIN being perfect...
And to the OP. Color coordinating your skis makes you a gaper. Just buy cheap stuff, and put the extra money in a savings account for when your a 22 year old college student like me, and you can barely afford rent and textbooks, much less blue bindings... You parents would probably be impressed.