The Karttika Vrata means, “Don’t eat, don’t sleep; just chant Hare Krishna 24/7!” The most auspicious and beneficial Karttika niyama-seva vrata starts on Ekadasi, Sunday 14th October and ends Uttana Ekadasi 22nd November 2015.
Most all Gaudiya Vaisnavas follow this rule as prescribed by Srila Sanatana Goswamipada in Hari-bhakti vilasa 16.168: Sri Krishna said, “Rani Satyabhama, one should enthusiastically start the Karttika vrata on Ashvina shukla Ekadasi.”
In 1972, Srila Prabhupada set the perfect example by observing the Karttika month in Sri Vrindavana beginning on Ashwina Shukla Ekadasi, and he advised his American disciples to do likewise. Before leaving America to go to India for Karttika, Srila Prabhupada said, “In Vrindavana, we shall have Urja vrata [means Karttika vrata] for one month. You also could observe Karttika vrata here [Los Angeles] from the next EKADASI for one month.”
When Srila Prabhupada arrived in India some disciples asked, “Srila Prabhupada, can you describe how to observe the Karttika vrata? Srila Prabhupada replied, “You should chant the Hare Krishna Maha Mantra twenty-four hours a day for one month. That's all! Yes! And don't sleep, don't eat. This is Karttika vrata.