Hi there. 

It is surprising to know that your school has already completed 8 chapters in Physics and you haven't started with any. 

Please start your preparation as soon as possible or else you will start lagging behind your counterparts. 

And there's no need to be confused with the idea of where to begin. 

Start with the 1st chapter itself and then keep moving forward. 

First read the NCERT of the chapter. Make a chart of formulas. Solve all examples and exercise questions of NCERT then solve multiple choice questions from Arihant Publications DC Pandey book. 

After that solve the previous year papers and you'd be done. Please start your preparation now or else you'll regret this delay later. 

Wishing you luck!