I am getting no clue about how to start with QA as 200 odd days remain what should i follow ?

Pick up a topic
Learn the basics
solve 10-20 questions (of that topic)

Finish arithmetic first ( ratio, percentage , P&L like this) then do either algebra or geometry, make 2 sections your strong point and then finish number system and modern maths

watch cracku's qa video on youtube. If you are a full course student, stick to the schedule and practice many questions as you can. Think in terms of numbers, there are 8000+ Quants questions in the study room. One who solves them will ace the QA section in Cat.

study that chapter in which all students are weak at not just any arithmetic dude. find out where students lack