Hi Arun, 

In my opinion it is a bit late to start preparations for NEET UG 2018 by studying new books altogether. However it is never too late. So my suggestion would be to not start with a altogether new book. It is better if you go thoroughly your NCERT books giving emphasis on each and every line specially of BIOLOGY as there is a tendency of paper setters to use similar language in the question papers. For chemistry and physics solve all the questions at the back of each chapter. And most importanly, solve as many as mcqs of previous year question papers in this small time As they only can give an idea of the pattern of the questions asked in NEET UG. Also please keep your doubts cleared at all points of time. Apart from these you can go through Aakash or Allen modules for further informations but before that you need to complete the ones i told you.

Hope this helped. keep working hard. All the best for the upcoming exams ! :)