Historical clue formulations

• First post-B.C. year — 2019-06-02
• Millennium starter — 2015-03-19
• I, historically — 2008-02-27
• Millennium starter — 2005-01-14
• Beginning of time? — 2004-08-14
• Start of a millennium — 2000-07-07
• I, to historians — 2000-04-13