While there is no right time to start the preparation for IAS, it is always advised to start early. Due to the vast syllabus, it is smart to prepare for it while you are still in college. Toppers like Tina Dabi started as early as her first year of graduation. Since this exam is based on a generalist approach syllabus, it becomes difficult to cover the entire syllabus within a year. So, an early start keeps you at an edge over others. In other cases where you feel you have already wasted too much time, you need not worry. There have been examples of people who have cracked this exam even when they started late in their careers. Starting early is the ideal way of going about it but not the only way.