Hello Subhodeep,

The strategy is simple:

Since you have already appeared for the exam(JEE main) you know your weak topics, first step would be to strengthen them. Next you should go for preparing any topics if you have left during your mains preparation. After then, since you will be left short with time, I suggest you to get a crash course of some coaching or get some previous year papers. Solving them and analysing your mistakes will help you increase your level. Apart from that, try solving high level books when preparing for JEE advance. Keep the syllabus of JEE advance in hand when preparing for it.

The syllabus is attached herewith for your reference:

https://jeeadv.ac.in/syllabus.php

https://engineering.careers360.com/articles/jee-advanced-syllabus

engineering.careers360.com/download/jee-advanced-ebooks