Every distinct wording since 2010, newest first.
June 10, 2022 · Commander Legends: Battle for Baldur’s Gate
A spell that states it may be cast “only before (or after) blockers are declared” is referring to the turn-based action of declaring blockers. It may be cast only before (or after) the declare blockers step begins, regardless of whether any blockers are actually declared. (See rule 509.)