@APS17
DGCA does not care for 11th . They only care for 10th and 12th
In 10th they want Maths and Science as subjects
In 12th they want to see Maths and Physics as subjects . You need to learn just enough to pass these papers ( which I believe is around 33% or 35% could be higher depending on which board you go to )
But you should have passed 12th overall ( not just passed in Maths and Physics alone )
How long it takes to study varies from person to person and the teacher teaching you . If you can score above 55% in Maths and Physics and English then you will be eligible for IndiGo Cadet Pilot Program and the IGRUA entrance as well