The last time there was any widespread early delivery of iPhones was in June 2010/iPhone 4. I was lucky enough to be one of those - and it was my first iPhone. Lots of people got those a day early on purpose due to issues with activation overwhelming AT&T when they all arrived on the same day for the previous release. I believe that was also the last launch of AT&T exclusivity (if I recall correctly, Verizon started selling the iPhone 4 around 6 months later).
I've only ever seen fakers post early delivery since, but I can imagine there are a handful that get out a day early. Lottery level odds for it being you..