I’m guessing it’s unfinished. I use Dunlop lemon oil and follow the manufacturer’s instructions on all my boards (ebony and rosewood). Should be fine for jatoba too. Some people use linseed oil oil, but be extra cautious when disposing of the rags used to apply it. If not disposed of properly, the rag contaminated with linseed oil can self combust. Also, if it’s extra gunky, 0000 steel wool can be used to get rid of the built up gunk. But be extra careful, tape up your pickups (especially if uncovered), because the steel dust will be everywhere and it can short out your pickups. I personally don’t use it. I rather clean my guitars regularly to avoid the need for such measures.
I’d say that a thourough oiling once or maybe twice a year should be enough. You don’t want your axe dripping with oil, it’ll only collect dust.