About a month. Generally, you will receive the admission notice from the graduate students of HKU in about one month. The completeness of application materials has a great influence on the time to produce results. As long as the materials are complete, it will usually be quick. If it exceeds, your materials may be incomplete or there is no reply in the email. You should keep in touch with the school at any time. I suggest you start applying in advance, and you are most likely to be admitted.