The devotees usually observe Navami Homa by reciting seven hundred verses from Durga Saptashati and likewise on each individual verse Aahuti is done. A person involves at least a period of time of two to 3 hrs for performing the ritual of Navami Homa in the ritualistic way. वास्तु भगवान, https://www.youtube.com/watch?v=QIX0JZlLsgE