Time management is very much important in IIT JAM. The eduncle test series for IIT JAM Mathematical Statistics helped me a lot in this portion. I am very thankful to the test series I bought from eduncle.
Nilanjan Bhowmick AIR 3, CSIR NET (Earth Science)
Deb dulal halder Halder
in general, you can consult the book Richard Tuck, Hobbes: A Very Short Introduction, Oxford: 2002.