“Aath Koti Nani Paksh” is not a universal Jain doctrine or a standard pan-Jain sect name. It is generally used as a local sangh/community or sthanak name in some regions, and its “beginning” depends on that specific place or tradition rather than on one fixed Jain origin. ( jainknowledge.com)

If you mean a particular Aath Koti Nani Paksh sangh in a city or a specific institution, the exact starting date would need that local reference. ( jainknowledge.com)