I knew for awhile, but pushed it down for a long time. It was probably 6 months after I realized that I couldn't hide it any more that I actually came out. Being in the closet is rough. My heart goes out to anyone that isn't able to come out.
I suppose I was closeted to myself for the first 19 years of my life. But once I was sure of my orientation I came out to all of my friends and family within six months. The only thing that made me wait for a while for most of them is I live so far away from most of my friends and family I waited until I could tell everyone in person. That made for a busy and conversation filled holiday season but I was lucky that everyone was and continues to be supportive of me.