Mahalaya is observed seven days before the Durga Puja festivities begin. In 2011, Mahalaya is on September 27 (in Bengali Calendars). It heralds the advent of Goddess Durga to earth. Mahalaya marks the beginning of ‘Devipaksha’ and the countdown to Durga Puja. The day also marks the end of the Pitr Paksha in
Mahalaya is basically an invitation for Goddess Durga to descend on to the earth. The day is spent in chanting mantras and singing bhajans. The most famous being the – ‘Jago Tumi Jago.’ The Chandi Kavya or Chandi Stotram is recited on the day.
Mahalaya is also the last day of the Pitru Paksha. Prayers are offered to dead ancestors on this day during pre-dawn hours through the Tarpan ritual.