While it looks like nostr:npub1xtscya34g58tk0z605fvr788k263gsu6cy9x0mhnm87echrgufzsevkk5s published NIP-57 on Feb 13 2023 he did it Satoshi style and published the code first to GitHub on Feb 10 2023. People were able to start testing it that day I remember. It was a Damus only thing at first.