Ostara, the beginning of spring is in late March.

Idk the roman republican calendar began years at kalendes Ianuarius, and they were absolutely pagan. It looks like the germanics and celts did it in mid winter too, though they started summer quite early. If it holds any truth it’s probably about the Celts beginning their calendar in late spring/early summer. Looks like Babylon did it like the celts.

Idk modern paganism is basically entirely reconstructed or constructed whole cloth in the modern era. Extant traditional polytheism is generally separately categorized. The wheel year most of us use comes from Wicca which was created in the 50s.