Since everyone else on teh internet can make up their own terms for whatever music they're writing about and then apply it to just like all music ever, I'm going with this term - PROTO-PROG - to cover American garage/sike jumping to period prog/math rock. COOL?! I've learned online you can say a group like the Turtles or the Beatles are considered proto-prog since they played music before 1969. C'mon, like, the peeps who write for teh internet say so: "amost (sic) everything before 1969 is proto-prog." DUH!
Everyone knows about the Music Machine, right? Like, "Talk Talk" is a Nuggets classic. Oh, and their psychedelic groover "Eagle Never Hunts The Fly" is canon as its gotta be one of the toughest American sike tracks ever commited to wax. Well, a lesser known MM jam, "You'll Love Me Again," has got to be one of the first official American steps towards math rock/prog. It then is (ahem) proto-prog, as it's syncopated and jerky while still being punk/tough as fuck AND clocking in at under two minutes. This song makes me feel like I took a TON of acid and then did my algebra homework successfully.
The Music Machine was always all about weird syncopation and odd tunings, so to consider they just beat out the English at being the first to go "progressive" doesn't surprise me.