You can start your revision with the topics which you have completed and which carries more weightage in the exam. You can take help of NCERT books for revision or important notes which you have prepare.
Go through all the formulas.

Practice and revision is a key to success. Refer previous year papers, complete mock test series and MCQs for your practice. Understand your strength and weakness and work upon them.

Don't pick any new topic or reference book. Revise all the topics which you have done thoroughly.

All the Best!!