Beginning October 21, we’ll all be under the influence of Mercury retrograde’s pre-shadow or retroshade. This two-week period is a precursor for the main event of Mercury retrograde, which begins on November 9 in the free-wheeling, free-speaking sign of Sagittarius. “The countdown to chaos is on as mix-ups, misplaced items, and messy energy start creeping in,” Cindy Cavota, productivity coach at Headway , told The Post. When does Mercury go retrograde? Mercury enters its pre-retrograde shadow