How soon a motion for summary judgment may be filed depends on whether the plaintiff or defendant is the moving party. The plaintiff may not move for summary judgment until after: (1) 20 days have elapsed after the commencement of the action or (2) service of a motion summary judgment by the defendant. Mass. R. civ. P. 56(a).
The Defendant may file a motion for summary judgment at any time, as may any defendant-in-counterclaim or defendant-in-crossclaim. Mass. R. Civ. P. 56(b).
Both plaintiffs and defendants must also file their motions not later than 10 days before the date on which the motion will be heard. The Tracking Order applicable to a Superior Court case will also specify the date by which motions for summary judgment must be filed.