Sir,i'm in first year in cse in surat and after my b.e degree i got addimision iim ahmedabad so i'm preparation cet exam.inform cet tutorial

I'm in fy in cse in surat and after my b.edegree i got admission in iimahmedabad so please inform me abot cet preparation time duration and tutorial in surat.and which degreeis best in future cse or eceit? is not related iim. in future i'm not get iim so i can go astrophysics in nasa.please answer.