May 25th, 1983.
No, I'm not being flippant. I called in sick so I could go to the theater opening day. That was my demarcation (I hated it). I only really acted on it years later when the SEs were announced (or released, I forgot which). That action was searching for a way to have DVDs of the theatrical versions of first two films. Which, for the unwashed, is how I discovered this community.