When is the beginning of Fall?

 Autumn or Fall begins either around the beginning of September / Labor Day weekend

For 2022, that will be Thursday Sept. 1, 2022 or Monday Sept. 5.

Meteorological Autumn can be observed as early as 9/1 annually or technically

the Astrological Autumnal Equinox begins precisely at 9:04 p.m. 9/22/2022.

https://www.almanac.com/content/first-day-fall-autumnal-equinox