Mine was in '96 when the 'Toon was re-elected - an absentee ballot at that, as I was in Germany in the AF at the time.
What a let-down THAT was. Ugh.
My first presidential vote was for Goldwater for President. They told me that if I voted for Goldwater we would soon be in a land war in Asia. And they were correct!
I'm sitting here trying to remember my first Presidential vote. I think they lowered the Federal voting age to 18 just before I got to that age. If that's the case, my first vote would have been when I was 19, in 1972, for Nixon. Say what you will about Tricky Dick, I shudder to think what this nation would look like today if McGovern had been elected President during that time in our history!