According to this post, Trump was physically at the rally and could have started the speech on time: https://greatawakening.win/p/11RhFbQ2gV/if-trump-knew-that-pence-would-b/
I would assume team Trump knew what antifa was going to do at the capitol building, so they left "on time" so Antifa thought the clock was ticking. Then they waited and MADE SURE the speech went long so the majority of Trump supporters WERE NOT there when they tried to breach the capitol building.
As I was watching the speech I kept wondering to myself why the hell he was still talking while the voting was starting. I eventually stopped watching the speech to watch the voting. I went on a drive to clear my head when I realized it was going to take all day. 20 minutes later I was back home and the capitol had been "overrun"...I thought to myself..."That was fast."
I also found it weird that the speech was announced just the evening before. Yeah he asked us weeks ago to come to DC but the speech itself was practically last minute.