Between shooting Disney’s “Oz: The Great and Powerful,” opening the Weinstein Co.’s “My Week With Marilyn” and being a mom to a 6-year-old, Michelle Williams doesn’t get much sleep. So when the actress recently curled up on a private jet headed from New York to Detroit, where “Oz” is filming, her team had the pilot circle for 90 minutes so she could doze. “They had the plane circle so she could sleep as long as possible,” a source said. “Then she went straight to the set. She’s had 5 a.m. call-times.” Williams was back in town Sunday for the premiere of director Simon Curtis’ “Marilyn” and party at La Petite Maison. Kenneth Branagh also flew in from London for the event.