You'd better contact now. Anyway, we can apply during the military training, that is, before the formal class. I used to be in the information department, and one of my classmates switched from business as soon as he came in. Military training is already in our class. I have a junior majoring in mechanical and electrical engineering who has been studying for one year. It turned out to be too difficult because he studied liberal arts before. The result was also transferred to the Foreign Languages Department. Anyway, I remember that it can be changed within one year, but the sooner the better. Otherwise, wasting a year is really boring.