I’m on mobile but maybe I’ll do it later. Or one of you could claim the honor of discovering and sharing it.
Initially I suspected that all the people on the actual-first-day weren’t actually people — that pg seeded HN during its early days, much like Reddit, with multiple personas that only seemed real at a glance.
But now I think pg emailed a link to all@ycombinator.com and those initial users were the people from the 2005 batch. Then they collectively lost interest (which accounts for the multi month gap) at which point pg made it public as Startup News.
I would give a hint on how to find the real first day, but I think I like leaving it as an open puzzle. As a hint, pay close attention to the URLs on the page that this submission points to.