Since when has the dish required to be made in the first round of Time Machine Chefs been prepared?
Time Machine Chefs: Time Machine Chefs is a television special that originally aired on ABC in which four celebrity chefs were challenged to cook against each other using ingredients and tools belonging to a historical era. Time Machine Chefs:  The program was divided into two rounds; the first challenged the chefs to create a Peking duck in 16th century China during the Ming Dynasty and the second saw the chefs create a Cockentrice in 1532 in the House of Tudor. Peking duck: Peking duck is a dish from Beijing that has been prepared since the imperial era.
the imperial era