When were georgian and regency chairs invented?

Answer 1

Georgian times covered from George I to George III, so from 1720ish to 1820. Regency is more specific, covering the later period of the reign of George III during his incapacity. His son (later George IV), ruled in his stead as Regent.

Georgian and Regency chairs were not INVENTED as such. The term describes a styling and design influence from this period.