In what case is the pilot allowed to abbreviate the call sign of his aircraft?

Question

Question Quiz BPL Gas - Balloon Pilot License - Communication

QuizVDS · Accepted Answer

After the ground station has used the abbreviation

QuizVDS · Answer

Within controlled airspace

QuizVDS · Answer

If there is little traffic in the traffic circuit

QuizVDS · Answer

After passing the first reporting point

Id 113 - BPL Gas - In what case is the pilot allowed to abbreviate the call sign of his aircraft?