There was some talk show thing and the concept of "24" came to be even before 9/11!
Yes, it was written before 9/11. It came on TV either immediately before or immediately after 9/11.
I've been watching 24 since the beginning.
I read about it during the summer of 2001.
Without knowing too much what it was all about, I decided I was going to watch it because the "real time" aspect of the show intrigued me.