School placements for Archie and Lilibet were among factors in the timing.
The king and queen will remain in nearby Clarence House.
King Charles III is expected to reveal his personal tax bill on Thursday
King Charles III and Queen Camilla will spend most of the final day of their four-day state visit to the U.S. in the state of Virginia.
King Charles III and Queen Camilla paid tribute to victims of the 2001 terrorist attacks during a busy swing through New York City on Wednesday - the first visit to the Big Apple by a reigning British monarch in 16 years.
William and Kate were married on April 29, 2011, at Westminster Abbey.