You might say it even starts a bit earlier than that - with Buffy beating the Master in "Prophecy Girl" by using a well-established vampire trick: coming back from the dead.

Possibly completely coincidentally, Dawn snarks at Buffy in "Lessons" that her plan for fighting vampires involved getting killed and coming back to bite Buffy.

Buffy appropriates bits of both the vampire myth and the vampire slayer myth and uses it to forge her own. Gotta love a gal with an anvil.