Sade Sati is the seven and a half years in which Shani transits the twelfth, first and second from the natal Moon. It is felt as weight rather than disaster — work that does not move, recognition withheld, a tiredness that sleep does not fix.
Til oil is the dravya of Shani, and the tel abhishek is the rite prescribed for the period. The Special Pujas below are performed on a tithi you choose at the Navgrah Mandir on Triveni Ghat, Ujjain, so a Shanivar or a Shani Amavasya can be booked without waiting for a festival.
17 sevas at 14 Teerth Kshetras — you choose the tithi.
It depends on your natal Moon sign, not your sun sign. The free dosha tool on this site will show whether Sade Sati is running and which of the three phases you are in, from your birth details.
The 17 sevas here are Special Pujas — you choose the tithi yourself at checkout, so they are available year-round and are not tied to a fixed festival date.