Hello,
See,it's a good thing if you start preparation for any competitive exam at an early stage,most of the exams demand a candidate to attain 21 years age in order to appear for a exam and also they allow in most of the cases candidates in their final year to apply, so the sooner you start the better it is,specially with such increasing competition day by day if you start your preparation with full focus and determination, then you'll definitely succeed. You have to follow certain things such as be acquainted with syllabus, this is the most important thing in order to know what to read and skip, make a schedule to devote subjects accordingly, keep resources minimal, and reading newspaper such as The Hindu or The Indian Express on a daily basis, irrespective of the exam you're applying to,this is unavoidable in most cases.