When does possession legally occur for the hypothecation to be confirmed if the item is already held by the mortgagee?

Primary text

Al-Qadi and the companions of Al-Shafi'i hold that the hypothecation does not become established until a period elapses during which taking possession is feasible. For movable property, this is the time needed for removal. For measured goods, it is the time needed for measuring. For immovable property, it is the duration required for vacancy (Takhliyah). If the item is absent from the mortgagee, it is not considered possessed until the mortgagee or his agent arrives, and then a period allowing for actual receipt must pass, because the contract requires possession, which is achieved by action or possibility thereof, even if actual physical custody has not yet occurred.