Agniveshyagrihyasutra 2.2.1.1

2.2.1.1

saṃvatsare saṃvatsare ṣaṭsu ṣaṭsu māseṣu caturṣu caturṣu māsi māsi vā janmanakṣatre kriyeta \

Every year, every six months, every four months, or every month, [a rite] should be performed on the birth asterism.