Bhima Ratha Shanthi is scheduled for the date on which the person starts 70 years of age - Janma Nakshtra to be taken into account.

While on the subject let me give a list of such shanthi karmas hereunder:
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* One year old : Abda poorthi Ayush Homa
* Start of 55th year : Bheema Shanthi
* Start of 60th year : Ugra Ratha Shanthi
* Completing 60 years : Sashtiabdha poorthi
* Start of 70th year : Bheema Ratha shanthi
* Start of 72nd year : Eka Shanthi
* 77 years 7 months 7 days : Vijaya Ratha Shanthi
* Completing 80 years & 8 months : Satabhisheka - Sahasra Chandra Darshana [ have seen 1000 full moon ]
* Completing 100 years : Poornabhisheka (Kanakabhisheka)
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Of all the Shanthi karmas listed above, Abdha Poorthi, Sashtiabdha Poorthi, Bheema Ratha Shanthi & Satabhishekam are well known and performed by many.

Hear I may also add that there is one more Shanthi Karma which is known as Prapouta Shanti which is to be celebrated when a son is born to one's son's son.

SRI RUDRA EKADASANI:
One more information that every one of may be well aware of. When Sashtiabdha poorthi, Bheema Ratha Shanthi and Satabhisheka functions are done, Sri Rudra Ekadasani also is usually done as a part of the function. Sri Rudra Ekadasani is a prayaschitha karma and it is advisable to carry it out in a elaborate manner. It will do good to the entire family in addition to the individual for whom the shanti karma is intended.