We don't have synonyms for first period yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are first person.
(N) :
an American architecture style originating between approximately 1626 and 1725, used primarily by British colonists during the settlement of the British colonies of North America, particularly in Massachusetts and Virginia.
(N) :
an American architecture style originating between approximately 1626 and 1725, used primarily by British colonists during the settlement of the British colonies of North America, particularly in Massachusetts and Virginia.