Interesting question. First reaction is springtime, or early summer...to hit on the summer blockbuster thing. However...maybe they aren't shooting for a blockbuster here...maybe they want something else, something more solid...
So, my second reaction is winter. If they shoot a lot of snowy winter scenes (which seem to fit Wolvie so well), then I would love to watch a wintery film during the winter season (in the northern hemi). Ever watch a winter movie in the middle of summer - it just doesn't feel right.
Therefore, I'm going with December. Might tap into the Christmas break thing, and give older teens and adults something fun to watch will the little ones are watching a kiddie flick.
das