[nope96]

https://en.wikipedia.org/wiki/Big_N

"Nickname for Nintendo"

I remember it being frequently used as far back as the 80s by Electronic Gaming Monthly

[opello]

I replied in another thread [1] but this was the earliest thing I could find in online resources, but maybe your recollection would lead to something earlier:

https://archive.org/details/run-magazine-87/page/n17/mode/1u...

[1] https://news.ycombinator.com/item?id=44601355