Bought up in a non religious household so didn't need to come out of the atheist closet. Am happy to tell anyone I don't believe in beings in the sky! I also say that I respect their right to believe in what they want to.

My mom was an atheist and my dad an agnostic, so it would have been weird to come out as a theist.

My boyfriend.

I have been atheist for so long, that I'm not sure. A lot of people figured it out, when I declined church membership, and danced naked under the full moon.

One of my best friends when I was just out of the Army and back in a Community College getting my head cleared. I did not understand the concept of being Agnostic, but lived the life most of my life 'Being a Healthy Skeptic' and then I found Bart Ehrman, Christopher Hitchens along with reading the livers of Martin Buber, Erasamus, Wylcliff, Calvin and Jan Hus.

I was lucky enough to not have been brought up in a religious household, so I was never a believer.
So I never had that 'coming out' experience.
But as to the first person. hmm, i guess maybe in a conversation with some one who was religious, but I've had too many of those to remember when was the first.

My older sister. She eventually became a nun.

Never kept tap... Was Not That Important Then or Now!