The wardrobe supervisor may be present at some production meetings and fittings, their primary responsibilities generally begin at the load-in stage of a production and during prep of a film.
The wardrobe supervisor supervises all dressers and costumers working on a production.
In consultation with the production manager, stage manager, costume designer, and sometimes the director, the wardrobe supervisor helps to coordinate and assign dressers to specific performers and tasks.
Generally, the wardrobe supervisor decides whether a point in a production requires a quick change backstage, or if there is time for a normal change in the dressing room.
J. Michael Gillette Theatrical Design & Production Mayfield Publishing Company, Mountainview CA, 1992