Please guide me how to prepare strategy for iit jam 2021 from now onwards. which topic to start first and focus more

Considering your name, that is Aditi "agrawal", I could surely assume that you have no reservations!( or in the limiting case you you may have EWS reservation). So, I suppose you t...

now when you complete mp, then start with Electrodynamics, electronics ,optics.. atlast do quantum as qm is in 3rd year.do as much as question you can do... all the best

dear start with mathematical Physics, as this is in your 1st year syllabus , also it is easy subject and help you in other parts of physics too..

after that complete mechanics , thermodynamics, nuclear ,optics n all

like Quantum it covers maximum portion of exam, then complete electrodynamics

then dear prepare subjects whose weighage is high

first focus on mathematical physics it will give you foundation