Shani Jayanthi, is believed to be the day when Lord Shani, one of the Navagrahas made its appearance on Earth. On Shani Jayanti day, people perform special pujas at Navagraha Temples or in Shani Temples. Those Hindus having Saturn cycle or Shani cycle or Sade Sathi in their horoscope perform special pujas like Shani Yagya or Homa. Some devotees observe a fast (fasting or upvaas) on the day.
Shani Jayanthi is also known as Shanishchara Jayanthi and Shani Jayanthi. People perform Navgraha puja to the best of their abilities on Shani Jayanti to please the God. Large number of devotees are seen thronging at Shani Temples in order to ensure that good luck favors them.
Shani is believed to bring in best luck but only in a gradual manner that comes through patience and hard work. One needs to understand the importance of discipline to succeed in life. Maintaining consistency in life is something that is helpful in keeping the negative influence under control.
It is a very auspicious day to perform Pariharam for Saturn(Shani) on this particular day and Navagraha homam/havan.