Hello,

KVPY Stream SB consists of two parts, first is of 80 marks and second part is 40 marks, total questions are 120, in order to commence your preparation first of all be acquainted with the syllabus, you can refer the important topics of

Physics are Mechanics, Ray Optics, Electromagnetism, Waves

Mathematics are Algebra, Geometry, Basics of Number Theory, Quadratic Equation, Progression and Series, Permutations and Combination, Basic Geometry

Chemistry are Physical Chemistry, Atomic Structure, Chemical Bonding, Chemical Energetics, Organic Chemistry, Stoichiometry and Gaseous State

Biology are Biomolecules, Molecular Genetics, Cell Biology, Biotechnology

Make a timetable, accordingly assign number of hours for each subject,choose the appropriate study materials, NCERT is the best choice regarding this, apart from it you can also go for other reference books such as

Physics

Fundamentals of Physics by David Halliday

Robert Resnick, Jearl Walker; Concept of Physics by DC Pandey

Tata Mc. Graw Hill’s Book by HC Verma

Chemistry

Moderns ABC of Chemistry for Class – XI With CD by Modern Publishers

NCERT Physical & Organic Chemistry by OP Tandon

Biology

Biological Sciences by Taylor Green and Stout by Cambridge Publications

Elementary Biology (Volume – 1) by K.N. Bhatia

M.P. Tyagi; Publisher: Trueman

Mathematics

A Das Guptha, Mathematics for class XII

Problem in IIT Maths by R.D.Sharma

Be thorough with the syllabus of 10,11th, 12th,  make short notes if requires, revision is  the key to excel in exam, go through previous year papers, apply mock on regular basis in order to evaluate your preparation level.