The change of a particular branch takes place at the beginning of the second semester. In fact, it depends on how hard you have worked for it. There are several students from branches of ECE, Electrical, and Mechanical who have secured themselves an upgrade to CSE.
Thus, your branch does not affect anything and can be upgraded if you have good marks. Now, to acquire an upgrade, especially to a branch-like CSE, you have to be a 10 pointer. It is because you are required to compete with students from various other branches as well.
That means you have to work quite harder to achieve a good performance in your mid-semester examinations, quizzes, and end-semester examinations as well.