Well, noone knows, or #asknostr has died.

For the curious, not even LLMs can decide:

GPT-OSS 120B

April 23 2023 – the date when the Nostr protocol was first announced and released.

GPT-5 mini

Nostr’s birthday is October 22, 2019 — the date when the nostr protocol’s first public commit (by creator @fiatjaf) was made.