I’ll answer in simple Deravasi (Shwetambar murtipujak) view.

1. According to pure Jain Dharma

- There is no real “sutak / ashoch” for puja. - Even if your father’s sister (bua / phoi) has died, you can do dharmakriya (Navkar, chaityavandan, samayik, etc.) and even go to derasar. - Death of someone else does not make your atma impure.

1. According to common Deravasi maryada

- For very close family in same house (mother, father, husband, wife, own children, real brother/sister living together), many follow: - No murti‑puja, abhishek, aarti, going in garbhagruh for about 3 days. - For other relatives (like father’s sister) where you do besana in a hall, not their home and not your home: - In many sanghs, people only keep niyam till that besana day. - From next day, they start normal derasar puja again.

1. So in your case (father’s sister, besana in hall):

- From Jain dharma side – you may do puja immediately, even that day. - From maryada side – most Deravasi will allow full puja from the next day after besana, because: - She was not in your own house, and - You did not stay in that house, only went to a hall for besana.

1. What is best to do

- If your local derasar or guru has a written / spoken rule, follow that first. - If there is no clear rule, it is safe and respectful to: - Keep that one day simple (more bhav‑bhakti, Navkar, prarthna). - From the next morning, start normal derasar puja.

You can read more about puja after death in family here and here