Srimad Bhagavatam Canto 06, Chapter 19, Text 21

SB 6.19.21

etena puja-vidhina
 masan dvadasa hayanam
nitvathoparamet sadhvi
 kartike carame ’hani
 
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
The chaste wife must perform such devotional service continuously for one year. After one year passes, she should fast on the full-moon day in the month of Karttika [October-November].
Srimad Bhagavatam Canto 06, Chapter 19, Text 19-20
Srimad Bhagavatam Canto 06, Chapter 19, Text 22