Day One. Where No Man Has Gone Before used footage of The Cage. As did The Corbomite Maneuver AND The Man Trap (depending on your definition of Day One). Most episodes ended with the final shot of the Enterprise from Where No Man Has Gone Before. Heck, the season 2 and 3 opening credits are exclusively footage from the pilots.
I think it was our own
@aridas sofia (who will no doubt be annoyed at being invoked in a SNW thread

) who first put pen to paper in a sort of "Grand Unified Theory of Enterprise Evolution" - including publishing a packet of drawings called The Enterprise Heavy Cruiser Evolution Blueprints. Although the various "classes" of Enterprise (Constitution, Bonhomme Richard, Achernar, and of course Enterprise) had been showing up in his work through the mid 1980's.
It's a lovely idea, but it's not really borne out by the literal footage.