Mam , I am eligible for KVPY 2018 .I am passed 12 th exam in March 2017 with PCMB 75 %.

Officially, the criteria for Stream SB is:
Students enrolled in the 1st year of undergraduate program in Basic Sciences namely Physics/Chemistry/Mathematics & Biology leading to B.Sc./B.S./B.Stat./B.Math./Int. M.Sc./Int. M.S. during the academic year and having secured a minimum of 60% (50% for SC/ST/PWD) marks in aggregate in MATHEMATICS and SCIENCE subjects (Physics/Chemistry/Biology) in the XII Standard Board Examination. In the 1st year final examination of B.Sc./B.S./B.Math./B.Stat./Int. M.Sc./Int. M.S. they must secure 60% (50% for SC/ST/PWD) marks before taking up the fellowship, if awarded.


So you are eligible for this scholarship program in your first year and later it can be a problem.
There is no age limit or gap criteria officially mentioned so you can apply!

You will have to apply for KVPY SB stream as students enrolled in the 1st year of undergraduate program in Basic Sciences namely Physics/Chemistry/Mathematics & Biology leading to B.Sc./B.S./B.Stat./B.Math./Int. M.Sc./Int. M.S. during the academic year 2017–18 and having secured a minimum of 60% (50% for SC/ST/PWD) marks in aggregate in MATHEMATICS and SCIENCE subjects (Physics/Chemistry/Biology) in the XII Standard Board Examination. In the 1st year final examination of B.Sc./B.S./B.Math./B.Stat./Int. M.Sc./Int. M.S. they must secure 60% (50% for SC/ST/PWD) marks before taking up the fellowship, if awarded.

For more information, you can go through the below provided link -

Eligibility Criteria

Hope this helps!!!