SB 6.19.21

etena pūjā-vidhinā
 māsān dvādaśa hāyanam
nītvāthoparamet sādhvī
 kārtike carame ’hani
Word for word: 
etena — with this; pūjā-vidhinā — regulated worship; māsān dvādaśa — twelve months; hāyanam — a year; nītvā — after passing; atha — then; uparamet — should fast; sādhvī — the chaste wife; kārtike — in Kārttika; carame ahani — on the final day.
Translation: 
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 Kārttika [October-November].