1797
Paine proposes a capital sum for everyone at 21
In "Agrarian Justice", Thomas Paine proposes a national fund paid for by a tax on inheritances. Every person, rich or poor, would receive £15 at age 21 and £10 a year from age 50, as compensation for the private ownership of land. Universal and unconditional.
Source: Wikipedia, Agrarian Justice, BIEN, history of basic income