Here are a couple of things I noticed that this article got wrong.
Firstly, the first month is not Tishrei. It is Nisan, the month of the Exodus from Egypt. That is in the Spring.
Rosh Hashana is on the first of Tishrei, the seventh month. That is in the fall.
Also, Rosh Hashana is believed, by Jewish tradition, to commemorate the 6th day of creation. The creation of Adam (Man). Not the 1st day of creation.
Also, Jews believe that Moshiach will be born on Tisha B'Av (the 9th of Av... in the Summer).
These three points make this article you posted very difficult to take seriously.
The parts that I find compelling are that he came up with that date before it was politically significant and that "the last trump" is an ironic coincidence when reading it today. I don't really know a tremendous amount about the other stuff.