On which day is Brahmin Bhoj performed during terahvi — day 13 itself or after Sapindikarana on day 12?

Brahmin Bhoj during terahvi is performed on the thirteenth day itself, after all rites of that day are completed. The Sapindikarana puja is performed on day twelve. The terahvi on day thirteen serves as the culmination: the mourning period formally ends, Ashoucha is lifted, and the family hosts the Brahmin Bhoj marking the transition back to normal life.