Detention is a compulsory measure, so once detained, you can seek help from a lawyer as soon as possible.
Legal basis: Article 33 of the Criminal Procedure Law of People's Republic of China (PRC). A criminal suspect has the right to entrust a defender from the day when he is interrogated for the first time by the investigation organ or takes compulsory measures. During the investigation, he can only entrust a lawyer as a defender. The defendant has the right to entrust a defender at any time.
When interrogating a criminal suspect for the first time or taking compulsory measures against him, the investigation organ shall inform him that he has the right to entrust a defender. The people's procuratorate shall, within three days from the date of receiving the case materials transferred for examination and prosecution, inform the criminal suspect that he has the right to entrust a defender. The people's court shall, within three days from the date of accepting the case, inform the defendant of the right to entrust a defender. If a criminal suspect or defendant requests to entrust a defender while in custody, the people's court, the people's procuratorate and the public security organ shall promptly convey it.
If a criminal suspect or defendant is in custody, his guardian or near relative may also entrust a defender.
After accepting the entrustment of a criminal suspect or defendant, the defender shall promptly inform the case-handling organ.