Start a very high energy preparation for ateast 5 months before the date of the entrance exam. But you should start a silent preparation before 1 year atleast to crack with a good score in the exam.
Give special attention to some of the topics like
- Physical Geology
- Applied Geology
- Economic Geology
- The Planet
Check previous year question papers and go through the basics of each and every subject which is taught to you. The regular revision matters a lot more than any other things during the preparation time. At many points you will find that remembering all the things simultaneously becomes hard; make short key words based notes and map notes to quickly revise all points. All the important experimental questions, concepts must be written separately in a short note so as to keep them revising on one go this will help you in NAT type questions. Refer good textbooks and keep solving and analyzing the questions. Try to be more concise and precise over concepts and basic knowledge rather than running on path of blind.
All The Best
Thank you, feel free to ask any questions anytime