If yes, how to know when property prices are going to fall?
Yes, WHEN is always the most difficult question of who, what, where, when, why and how. In fact in 1912 Mises answered all of these EXCEPT WHEN on the subjects of Panics/Depressions/Recessions in an economy.
But if the central bank of Hong Kong is creating money out of nothing, then they have a bubble in something somplace. Now the rest of China clearly is in the bursting stage of a huge bubble brought about by money created in a futile race to devalue the local currency relative to the US currency.