For invention patent applicants to request priority examination, they should make a request for substantive examination and pay the corresponding fees when they are ready to start substantive examination.
If a utility model or design patent applicant requests priority examination, it shall be submitted after the applicant has completed the payment of the patent application fee.
For patent reexamination and patent invalidation cases, you can file a priority examination request after paying the patent reexamination or patent invalidation request fee until the case is concluded.