You can prepare for JEE 2018, there is enough time. You should be determined and motivated to crack your exam. 

 You can follow below strategies to prepare for JEE 2018-

 PHYSICS:
Note down the formulae and results, it will help during revision.
Practice as many questions as you can, keeping in mind the availability of time.
Avoid lengthy and complicated problems at the last minute, if time is limited.
Focus on your strong areas.
Suggested Reference Books: H.C. Verma & Resnick Halliday

CHEMISTRY: 
Chemistry is amongst the tough subjects as it involves cramming of formulae and reactions.
Understand the conceptual base of the topics.
Periodic table is the most scoring part.
Suggested Reference Books:  Morrison & Boyd and O.P. Tandon
MATHEMATICS:
Conceptual understanding should be preferred.

Practice a lot.

In Mathematics JEE (Main)-2013, 32% questions were easy, 58% Medium level and 10% difficult.
Suggested Reference Books:  R.D. Sharma, Arihant, Hall Knight & S. L. Loonely

This is enough time if you give the time with quality to your preparation.

Hera are some tips and tricks to crack JEE main 2018 examination in just 6–7 months.

• Manage your time and always prepare more for chapters you are weak in, it will help you to not loose marks in the examination.
• If you are well in a topic then prepare that well it will help you to score more in the examination and it will also consume less time to revise.
• Once in a week, go through those chapters you are not comfortable in.
• In the examination month, Avoid preparing for new chapters, it will help you to avoid extra stress.
• Give more time to online mock test and don’t waste your time to searching all day long for that. You can get mock tests available on many websites. Once you find JEE main mock tests then Bookmark that page to use that another day.

Good Luck!