when and how should I start preparing for ssc or jssc . I am in my second year of graduation.

Before you start with the preparation, see the detailed syllabus for the exam to know the detailed break-up of various sections and the probable mark-distribution. Now, first of all, make sure you know everything about the latest SSC CGL exam pattern.

• Topics like Puzzles, analogy, coding-decoding, series, figure-based questions, etc. are very scoring. Start with these and move on to more versatile questions. You will notice a massive improvement in your accuracy within a week if you practice consistently.
• Nonverbal reasoning topics like image assembling, figure-counting, etc. require you to employ visual imagination. Do not skip or ignore these questions because they seem time-consuming to you. Solving them is the best way to make them less time consuming.
• Static GK mainly pertains to Culture, Indian History, Geography (India+World), Environment, Economy and Polity. Instead of cramming mindlessly, make notes and mindmaps to remember facts, chronology of events, cause and effect, etc. Doing this will also make your revision process quicker. Practice at least 75 questions of GA everyday within 30 minutes.

Also do not forget to solve the previous year papers to know how exactly you can get the paper.

Hope this helps.
Good Luck!