The 80s ended in September 1991. One week “Use Your Illusion” was released, which meant it was still the 80s then. The following week “Nevermind” was released, so obviously the 90s started sometime during that week.

This is terrific, I’m totally stealing this line to drop at my next dinner party.

early nineties ?

Extreeemely late eighties

Nineteen eighty twelve.

1992, the year that was late to the 80's