Hello,

It depends on what is your priority right now, if you're immediately looking for job after graduation you can start off preparation in gradual manner from college itself, from final year onwards you can become more dedicated if you're able to manage your studies and preparation well together, see anyway the recruitment process of any government isn't a fast process, ssc cgl is also conducted over three phases, so if you feel again pursuing MSc and preparing for the exam you can do well in both you can go ahead with it, eventually it's your decision, but you  also have to remember that over the year SSC CGL has become highly competitive exams, so you have to be extremely dedicated, focused in  your efforts, eventually it's all about being able to manage your studies and exams well, there are many people who not only along with studies but even with jobs qualify tougher exams like UPSC which has more extensive syllabus, and it has got more to do with how well-defined your schedule is, so think through it all with full clarity and accordingly take a decision, all the best!