In my personal experience, I first heard of it 1 year ago in a online forum game, people sold gold for Bitcoins, around March, gave it no importance at first. Now im kinda utterly commited to it. Really an interest subject of study.
I first heard bitcoin just months ago from my co workers who were once also curious about Bitcoin. I wasn't able to take time to read about Bitcoin then. But just this month i was then encourage again by a friend. This time, i gave time to read about it and ask a co workers about to gain more knowledge on how Bitcoin goes. I'm still on the process of learning thus i keep on reading.