Setting your iPhone’s date to January 1,1970 won’t bring up a cool new retro theme; it’ll just possibly break your device. Resetting your phone to the mentioned date will permanently power the iPhone off and lock the user out. On February 15, 2016, Apple confirmed that the bug does exist and to look out for an upcoming software update which will address the issue.
FYI, January 1, 1970 has no significance to Apple, the Apple I was actually released in 1976. If you cannot locate any updates on the Apple site itself, then I would not trust it.
Thanks to my buddies April & Canasia for the assist!