I think a good place to start would be to review how the 1987 Harmonic Convergence event was organized back in 1987 where the main location for that event was just outside of Oaxaca next to the El Tule tree of Quetzalcoatl.
And on that date, people the world over also congregated to other sacred grounds, mountain tops, mesas, stone circles, islands, beaches, waterfalls
etc... The date for this "synchronic reverence' was Aug. 17, 1987. It was a very successful planned event organized on a global scale.