I think 245–250 marks should be sufficient to get rank 5000. Its not easy to get the rank below the 5000 or 5000. you need to do hard work for getting the marks between 245-250.

I will suggest some tips for your preparation.

1. First of all you should do hard work. you have to set the goal.

2.  JEE needs dedicated preparing.  Some times you may lost your patience at these vast syllabus. so guidance is required to bring you to the right path.

3.  You have to prepare your own time table.

4. you have to attend mock tests as much as you can.

5. Sometimes you may feel you can't do it, you may feel stress, you may get irritation. At that time you need motivation. Motivation will gives you the strength.

6. Last but not least. you need to take care of your health. you need to eat healthy food.

I hope this will be help full for you.

ALL THE BEST