Neal was in his 20’s when he met Emma we think. He mentioned having worked as a janitor at the watch place, so presumably he was in the States for at least a year perhaps but we don’t know. He could have been anywhere from the time he left NL at 14, so who knows.
Still between people speculating that time doesn’t move in Oz, and Neal’s lack of knowledge of it, I don’t think it would seem like Neal ever met Zelena. He’s more likely her half- brother anyway at this family tree rate.
“If I had a world of my own, everything would be nonsense. Nothing would be what it is, because everything would be what it isn't. And contrary wise, what is, it wouldn't be. And what it wouldn't be, it would. You see?” -- Lewis Carroll, Alice's Adventures in Wonderland & Through the Looking-Glass