Here are some dates that you will want to keep in mind:

Schools in Hong Kong generally start in September and end around mid July. Thanks to the colonial history of Hong Kong, the local celebrates both Chinese and Western festivals and holidays as well. There are approximately 90 school holidays in a school year. For more details, you can check a sample calendar from the Education Bureau website for a more detailed calendar : Calendar_1718_Eng 

Most student in Hong Kong will also enroll in the Cambridge Young Learners Exam, so it will be fair to say that you will be requested to teach classes based on the Cambridge curriculum as well. Some dates to keep in mind when assisting students in these exams are as follow:

Cambridge Young Learners Exam: between May to August 2018

# For Starters and Movers Levels only
^ For Movers and Flyers Levels only

(Repost from The British Council)

You don’t want to miss out on the exam dates when doing your lesson plannings!