/gingerly raises hand
The first time was when I was fresh out of secondary school and was placed second in an annual international comic competition held by Kodansha's Morning magazine. I had an editor assigned to me but I felt I wasn't ready in terms of skill, knowledge and emotional maturity to take the pressure.
The second time was when I went to a convention in Tokyo a couple of years ago and there were booths where comic creators pitched in their works to manga magazine editors. I went to Morning again and showed them the first chapter of Undying Happiness. He liked it and gave me his business card, which was an indication that he's willing to work with me. But that year, I received a job offer from another company and didn't take the opportunity again.
Who knows, it could have been the biggest mistake I've ever made, lol.