As long as you register for WSET course, you can apply for the exam one month in advance after completing the course. The exam results will come out in a month or so. If you pass, you will be awarded a certificate.
There are many places to learn. I signed up for the study in Yanyun Wine Institute. Their home is the only institution in China that only focuses on WSET training, and it is convenient to start classes all over the country. Teachers are also relatively strong. It is said that their founder is a candidate for wine master, and no one in China can take this title yet.