Nothing is impossible but!!!!!!!!

Following needs to be considered:

Every individual may be different in intelligence, mental capacities, capabilities, stress handling and determination. Some may find four months sufficient time for preparation and some may find even one year less time. If you have good educational background, If you are good at english expression, grammar and composition etc, if you are somewhat familiar with current affairs, major obstacle is already corssed and four months may be sufficient. Many people have cleared the exam with only four months or so preparation.

Passing and Competing are two different things. You don't have to pass the exam only rather you have to compete agaisnt thousands of candidates for limited seats. Passing the exam will be of no use if you stand lower in merit to capture your dream group. I don't know about your domicile, but candidates from Punjab could not afford to just prepare enough to onlypass the exam falling in lower merit. They haves to prepare enough to secure around 700 marks in written for allocation to top groups. Now, if you think you can prepare well enough to cover your syllabus contents and get a good grip on these, you may appear for CSS 2012.

If you don't lose any CSS chance by not appearing in CSS 2012 and you have intact your all three chances even after CSS 2012, there is no harm in not apperaing if you feel not well prepared at the eleventh hour.

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Best end of life is not knowledge but action.
Don't limit yourself to what you think people are expecting!