Historical clue formulations

• End of an act, maybe — 2024-03-27
• One of two in "Hamlet" or three in "Macbeth" — 2018-07-27
• Part of many a Shakespearean act — 2013-12-17
• In Act I, it begins "Enter Ghost and Hamlet" — 2011-05-03
• Part of an act, perhaps — 2009-04-29
• End of an act, maybe — 2007-02-18
• Part of the act when King Richard III dies — 1999-06-19