Here's what I've compiled so far...
Here Come the Warm Jets (1974) – Brian Eno
I'm sure there are more songs to choose from because Eno's an innovator of his time, but this song in particular sounds eerily similar to the UK shoegaze era from the late 80s/early 90s. It contains those trademark abstract, fuzzy guitar distortions and obscure, indiscernible vocalizations toward the end of the song. However it's from early 1974, about a decade and a half before shoegaze even existed. I would have never guessed it was from that period if I hadn't known before.
Cupid Come (1988) – My Bloody Valentine
Speaking of shoegaze, this song is from 1988, but sounds like it could be an alternative rock song during the early to mid-1990s. It doesn't seem reminiscent of the late 1980s, imo.
I'm So Green (1972) – Can
This is from 1972. I would have imagined a date set possibly within a few decades later. I can hear a late 1980s Madchester à la Stone Roses sound in this. In fact, it also has an early 90s indie rock feel to it as well.
30 Seconds Over Tokyo (1975) – Pere Ubu
Post-punk pioneers. An early 1980s post-punk sound, but from 1975. It's probably because of the staggering guitar riff in the background and the gloomy, offbeat lyrics.
Autobahn (1974) – Kraftwerk
I would have to say this song and the whole album in general along with their other 1970s albums are a prelude to the 1980s electronic sound, complete with synthesizers and all. However, this is from 1974...
1974. Incredible, really.