Post-Millennialists (traditional Calvinist perspective) defines "End Times" as a progressively occurring event. Pre-Millennialists (dispensationalism) defines "End Times" as a definitive event.
Only Christ knows the "definitive" moment (coming like a thief in the night). To attempt to apprehend the definite moment of "End Times" as Christ apprehends it as God-man is the error that is taught by dispensationalists, and traditionally avoided by Calvinists.
I hope this clarifies the issue.
I appreciate your efforts.