I managed to import some old tweets to Nostr with @PABLOF7z​ 's exit.pub Here my oldest tweet (July 2006).

nostr:nevent1qqstde2ru7xxul59j6a5rtfe3rmutyzfs4qrl7uqc20qvstxevzl8kcprdmhxue69uhhyetvv9ujumn0wd68y6trdpjhxtn0wfnj7q3qdg7n7g8440wrrqkw2kz88gqrvde0nasfnhxxu64l5pc7x6jkn0xqxpqqqqqqzv72f5l