I was in my teens when the films were in the theaters (11 in '77, you do the math on the rest) and some of my first younger cousins were born right around that time (oldest of them was born in '75) and this particular one has his younger sister in it, so I'd say it dates to around '79 or '80.

Bobby (the little cousin, about 4 or 5 years old), my sister and I are playing with SW figures on the floor. I forget who had which figures but we were acting out one of the scenes from the film. Kristin, Bobby's sister (about 2 years old) just shows up out of nowhere, Greedo in hand, and gets right into the action...

"I PLAY TOO!"