Yes it is good to attend the pre admission orientation of TISS as it aims at the following:

• It is organised by the Social Protection Office for all SC/ST/ OBC/PWD/Minority candidates who have qualified to appear for the National Entrance Test (TISS-NET) of the Institute. The orientation programme is scheduled for about 2-3 days in the month of November/December, every year.
• The objective of this programme is to orient them about the whole process of the entrance test, positive and negative aspects of written test, group discussion and personal interview. Besides, another important point which is touched upon is about the common mistakes that candidates make in the admission test and how to overcome those.
• The candidates are also told about the facilities available for the eligible candidates. It is all meant to help them feel confident. This is followed by clarification of any doubts from the candidates.

(Source:  TISS Official Student Handbook)

This shall be good to attend to boost your confidence as well as clearing your doubts if any.

Good Luck.