When did the pronunciation change from N-E-S to Nes?

When did the pronunciation change from N-E-S to Nes?

Of the people I knew as a kid, the “N.E.S.”/“Nes” divide was about even (I’m in the US)

I use both interchangeably, though the SNES is always just Snes.
I’ve never heard anyone refer to either as nes or snes, it was always spelled out.