What Trump really appears to be doing is not postponing the election, but sabotaging the post office so mail votes aren't counted or are very slow to be counted. Then claim victory on election night when results are ambiguous or slow to come in. https://www.washingtonpost.com/politics/postal-service-backlog-sparks-worries-that-ballot-delivery-could-be-delayed-in-november/2020/07/30/cb19f1f4-d1d0-11ea-8d32-1ebf4e9d8e0d_story.html

The key here would be to claim victory early, or at least create the perception that the result is unclear. Then put pressure on local officials to stop counting (through mobs or friendly judges). All this creates ambiguity in the perceptions of the judiciary and the military.

More evidence the actual plan, to the extent that there is one, is centered around the mail. https://twitter.com/markknoller/status/1289185984689524736

Preparing to sabotage the US Postal Service and use the chaos to declare victory. Sowing the seeds now. https://twitter.com/atrupar/status/1289247560578686977

They're trying to sabotage the election by sabotaging the Postal Service. https://twitter.com/atrupar/status/1289944610433667072?s=19

Trump's trying to sabotage the election by sabotaging the Postal Service. https://twitter.com/EllieRushing/status/1289880547536166912?s=19