When entering China, you will meet your guide/border fixer at the pre-decided border/day. The fixer will help you with the formalities and communicate with the border officials. He will carry all necessary documents and permits in the original. Without those documents the border crossing is not possible.
Afterwards, you will proceed to the next town to where the border checkpoint (administrative division) belongs to. In most cases this is the biggest town close to the border. It is for example Jinhong/Xishuabgbanna if you arrive from Laos or Kashgar if you arrive from Kyrgyzstan/Tajikistan/Pakistan. On the following working day after your entry you need to visit the traffic administration with you vehicle and undergo customs procedures (this depends on the border). The traffic administration will check you vehicle and issue your provisional driving license and provisional number plate beside other documents. The waiting time is often quite long. Plan accordingly. Once all documents have been issued, you can start your Overland journey in China.