When most of us hear the term “professional organizer,” we picture a decluttering maven who can alphabetize a pantry and color-code a closet in no time. But Sarah Giller Nelson, owner of Less Is More, an organizing service based in Miami and Chicago, says that lately, more and more parents are seeking her out for help organizing something arguably scarier than their chaotic basements: their crammed schedules. “Parents’ calendars are packed with school activities, birthday par