Ayusmaan homam is performed on birth days/ anniversary, praying to eight immortal personalities of Hindu Sanatan Dharma celebrating a birthday is way of expressing gratitude to God for all he has given to us in this life thanking him for what he has given us during the past year and praying for His grace in the coming year for healthy long life now days we received gifts on our birthdays, but in ancient time culture was to encourage one to give daana ( charity) on the day and after completing the Havan known as Ayusmam Homama