While friends were "beautifully supportive," Knight, 34, tells The Advocate in its June 19 issue, others cautiously advised him, "Don't do it – don't do it now."
Looking back, he says, "I remember saying to someone when I got one of those 'don't do it' [comments] – I just remember hearing my voice being calm and saying, 'No, it's going happen. It's going to happen. I'm just letting you know.' "
Ultimately, he's glad he decided to come out after castmate Isaiah Washington referred to him on-set by a homophobic slur. "I made the decision to make a statement," he says. "I could have not [spoken up]. I could have retreated. But I'm definitely happy I made the decision." (Washington has since apologized.)
Knight told PEOPLE in a statement in October: "I guess there have been a few questions about my sexuality, and I'd like to quiet any unnecessary rumors that may be out there. While I prefer to keep my personal life private, I hope the fact that I'm gay isn't the most interesting part of me."
Since coming out, Knight, who plays the unassuming Dr. George O'Malley on the hit ABC drama, has seen his character marry Dr. Callie Torres (Sara Ramirez) and bed fellow M.D.'s Meredith Grey (Ellen Pompeo) and Izzie Stevens (Katherine Heigl).
"I wasn't shocked or surprised. ... It was more just like, 'Oh, okay, now I know why you don't want to go out with me.' "
But Knight, who is single ("Not that I've had the most successful dating experiences," he says) insists coming out hasn't much affected his love life. He says with a laugh that he still assumes people aren't interested in him, but notes: "Too much aggression isn't a good thing either."