Jose do Espirito Santo was one of the Madieran Cabinet Makers that came to Hawaii on the Ravenscraig and have been credited along with Manuel Nunes, Augusto Dias and Joao Fernandes, (he was the player, not one of the Makers), with "Inventing the Ukulele. 

He set up as a luthier with his own Guitar shop in 1886 and he did make early Ukuleles as well as some of the other Iberian precursor chordophones like Rajaoes and Cavaquinhoes. Whilst it is not possible to say who was the first, Jose do Espirito Santo was the first of them to specifically advertise Ukuleles for sale in 1898. 

He died in 1905.