Historical clue formulations

• Once or twice — 2024-04-21
• Now or never — 2022-09-10
• Well, for one — 2019-09-08
• Sooner or later — 2014-05-02
• Always or sometimes, say — 2011-12-31
• Now or never — 2011-09-18
• Daily or weekly — 2011-01-02
• Always or forever — 2010-02-04
• Modifying word — 2001-05-23
• Adjective modifier — 1998-12-28
• 46-Down, for example — 1997-08-14