The seventh day of the sacred Mahalya Paksha which lasts for fifteen days is Saptami Shraddha. Tarpan and Pinda Daan for the ancestors who have died on Saptami Tithi irrespective of the paksha are performed on Saptami Shraddha. Pitru Paksha Shraddhas are Parvan Shraddhas and auspicious time to perform these Shraddhas is either Kutup Muhurat and Rohini Muhurat, else, one must wait till the Aparahana Kaal gets over. Tarpan is done at the end of the Shraddha.
The Pindas are then either immersed in river or offered as food to Cow. Proper care should be taken that the lunch during the process of Shraddha should be done during the Aprahana Time of the day which would be around 1-2 PM. Performing the Shraddha would please our ancestors would bless us with prosperity and wealth.