The case that was initially scheduled for 16 May was greeted with protest in Zinguinchor on Monday and claimed the lives of three people including a police officer.
Schools, banks and businesses were closed as a result of the protest.
Sonko has been accused of rape. Authorities alleged that he had raped one Ajie Sarr in 2021 while she was conducting a massage on him in a salon in Dakar.
At least 28 people including three policemen were reported wounded in Zinguinchor in Monday's protest.
Since the case started in February 2021, 18 people have lost their lives in protest.
Currently, 300 Sonko supporters have been remanded pending trial.
