You should try to figure out what major you will go into as soon as possible, because you want to make sure you take the right lower division classes. If you don't, it will be much harder to get out in four years. For graduation, each student must also satisfy general-education requirements determined by the student's college. The five colleges at UCSD require widely different numbers of general-education courses. Although you can join any of the five colleges, you should choose your college carefully, keeping in mind the special nature of the college and the breadth of education offered.
Some colleges require considerably more courses than others.
If you find that you want to transfer to another college, you should see your college advisor. Graduates of community colleges may enter ECE programs in their junior year. If you are a transfer student, make sure you check out the freshman and sophomore requirements pretty carefully. The EE, EP, and CE programs all have strong components of laboratory experiments and the use of computers throughout the curricula. After that, make sure to talk to them again at least once a year until graduation.