Fifth gen x86 processors were around 1994. So I'd guess earlier than that from the age of the machinery they're using.
But the 486 was seeing use in 1990. So after that but before 1994 would be my guess.
It's possible it was ongoing litigation at the time.
"Seeing use?" Maybe, but unlikely. When it was announced, it wasn't even going to hit manufacturing until 4Q1989. The first 486 computer wasn't even announced until just before Christmas of '89 and wasn't available until a long time later.
Widespread? Absolutely not.
In 1990, the town where I lived allowed locals to use its computer labs at off-hours. The machines were all 8088's. There was a guy I knew through the campus computer club who had an 80286, and he was considered "the future!"
I used to build my own computers, and I didn't get a 486DX2 until 1997.
Back then, people didn't upgrade major components all the time like they do now.