The earliest listing of the term "gentlemen (gentieux hommes)" I could find in the Calendar of Patent Rolls is 16 August, 1302. It is recorded at London involving "Assignment, sealed with the great seal, and with the seals of Edward, prince of Wales, the king's son, Richard,...." addressed to "the king's gentlemen". I would suspect that the concept of gentlemen had existed for a very long time among the social conscience. Webster gives one definition as "a man of independent means who does not engage in any occupation or profession for gain" [or a man who does not engage in a menial occupation or in manual labor for gain] In the context of 1302, these gentlemen "...who have served in the war Gascony against the King of France..." are given this title along with clerks and other "stipendiaries" (soldiers). [Calender of Patent Rolls, Edward I, vol. 4, 1302, p. 56.]
It would appear that this term had expanded its meaning and broadened its use, since in 1673, Cadwallader Jones (JO-1) was listed as a "Gent". [2 July 1673, see CJ(2)] The yearly income per head of household for the year 1688 was 35 pounds sterling for those classified as "gentlemen". Cadwallader spent "forty ponds sterling" for his land upon "the main run of Penmansind".