i do believe this was the first Navy Jack 
i do believe this was the first Navy Jack At the Congress, Continental Colonel Christopher Gadsden represented his home state of South Carolina. He was one of seven members of the Marine Committee who were outfitting the first naval mission.[6]
Before the departure of that first mission in December 1775, the newly appointed commander-in-chief of the Navy, Commodore Esek Hopkins, received the yellow rattlesnake flag from Gadsden to serve as the distinctive personal standard of his flagship. It was displayed at the mainmast.[6]
Gadsden also presented a copy of this flag to the Congress of South Carolina in Charleston, South Carolina. This was recorded in the South Carolina congressional journals on February 9, 1776.