Sri Jayanthi Nirnayam

 1) Only the solar month is taken into account.

     So it must be in simha (AvaNi) mAsam, which

     is mid-August to mid-September.

  

  2) The target date in this month is kRshna-ashTamI

     (8th day of the waning phase of the moon) in conjunction

     with rOhiNI. However, on that day, not even a tiny bit

     of saptamI should exist post-sunrise, nor should there

     be any kRttikA nakshatram.

  3) If there is no pure ashTamI-rOhiNI conjunction as

     described in (2), navamI-rOhiNi is the next preferred

     conjunction, with once again a pure rOhiNi mandatory.

  4) If (3) is not possible, mRgaSIrsha nakshatra combined

     with navamI or daSamI is the next preferred choice.

  5) If this observance of SrI jayantI does not fall on

     ashTamI, the ashTamI is treated as any other day and

     requires no special observance