when does the elf on the shelf start

Elf on the shelf is a Christmas tradition where a special elf doll is placed in a child's home around the beginning of December. The elf is said to watch the child's behavior throughout the month and report back to Santa each night. The elf doll can move around the house, but cannot be touched by the child, or it will lose its magic. The tradition is believed to have originated in Germany in the 19th century, and was popularized in the United States in the late 1990s.