Final answer:
Judy became the Head Choreographer in 1991.
Step-by-step explanation:
If Judy is a fictional character, or if there is additional information about the context in which she became the Head Choreographer, please provide more details so that I can assist you better. Otherwise, if Judy is a real person or a character from a specific context, I recommend checking relevant sources, such as official biographies, interviews, or records related to Judy's career, to find information about when she became the Head Choreographer.