Mine started to flower at somewhere around 6.5 years, but is finally holding a crop for the first time. It was planted 6 years ago as a very large 3 gallon.
The smaller one I have (which my wife says has a couple of fruit) may only be 6 years old. I don't remember when I got that one.
Actually, the vexator (when in the ground) is probably the least water hungry eugenia I have planted in the garden. It's the only one that doesn't need supplemental watering if we see a 2 to 3 week period without rain. I attribute it to the fact that the fribrous roots seem to be much more aggressive than the other eugenias I have. I remember potted vexators being fairly water needy though.
I've eaten a few vexators, and I wasn't all that fond them, due as saffron said, to the tannin content. But it's one of the few trees that I've kept more for ornamental reasons than for fruit enjoyment. It's compact, can take some shade, and absolutely beautiful.