1, you still have plenty of time. Mathematics is a basic course, which is very important for future study. You have to spend a lot of time studying, whether for the exam or for future research. I suggest you choose a set of economic mathematics textbooks and study hard. Since it is an interdisciplinary exam, don't choose too difficult textbooks. You can look at the textbooks of Sichuan People's Publishing House, and the textbooks of Tongji University are also good.

2, professional courses, you must learn macro and micro economics, which is the basis of other possible professional courses, this is not very difficult, as long as you carefully read the textbook three times, there should be no big problem. The classic textbook is Macroeconomics and Microeconomics edited by Mr. Gao Hongye, which may be more suitable for exam-oriented education in China. A better textbook is Pindick's Principles of Economics. I suggest you read Gao Hongye-style textbooks first, and then you can read Man Kun's principles of economics, preferably in English, and many other things. As for other courses, it depends on the school you apply for.

For other professional questions, I suggest you ask your classmates at the University of International Business and Economics. If you ask others, they may not know. Seriously, even people in our school may not know these things.