Start my own Hentai

Draw it. Then make a Patreon. Raise money and google doujinshi printers. Print. Sell at conventions. Contact Jacob and maybe he will host the digital and sell the prints if he finds he likes it.

Yeah, having something drawn and written is a good start.

First thing first, you need characters, and designing them is a good start.
the guy doesn't necessary have to be fleshed out, the girl is going to need lots of work.

This entirely depends on where you're trying to get published, as it is there's not a lot of hentai publishers in the west. As Freak said, get your work out there and show it to existing publishers.

Your first H-work more than likely won't get published, that's just reality. Work on improving your art skills and putting snippets out here and there.