At what moment during the approach should the reported airfield altimeter setting be set?

The transition altitude of an aerodrome should not be below:

The vertical position of an aircraft at or below the transition altitude will be reported:

The vertical position of an aircraft at or above the transition level will be reported :

Transition from altitude to flight level, and vice- versa is done: descent.

In the vicinity of an aerodrome that is going to be used by the aircraft the vertical position of the aircraft shall be expressed in:

The pilot of a departing aircraft flying under IFR shall change the altimeter setting from QNH to standard setting 1013.25 hPa when passing:

During flight through the transition layer the vertical position of the aircraft should be expressed as