If I start the preparation for jeemain now,can I score 150-180marks or 95percentile in Sept. I recently got the short notes of my brother,he written mains last year.

Hello,

Yes definitely if you have little bit concept based knowledge from the subject,you can achieve your marks.
Their are certain topic which are given more weightage and are easy.So if you give more importance to them and practice continuously with dedication,you are more likely to achieve your target.

But if you wish to start from NIL today and wish to get 180 marks,it's quite tough to be frank.

Hope it helps.