Was Homer being transcribed when written vowels were invented for the Greek alphabet?

Nestor’s Cup is one of the earliest inscriptions in Greek, and it’s got a metrical inscription that may allude to the Iliad:

So it’s feasible that Homer started being transcribed as soon as vowels were introduced—which pretty much was as soon as the alphabet was adopted in Greek. (We have no evidence of Greek using Phoenecian letters without vowels, and vowels were as much as anything a misconstrual of how Phoenician worked.)

The Iliad seems to have been written at roughly the time the alphabet was introduced, and writing is mentioned in passing in the Iliad: The “Fatal Letter” in the Iliad: Introduction of Written Language to the Greeks (Circa 750 BCE). But it’s likelier that Homer really was first written down when the Greeks said that Homer was first written down, two centuries later in Athens; oral transmission would have kept it around till then, and from what little we know, there was a lot of textual variation about, outside of the version that was written down.