The substantive examination fee shall be paid within three years, otherwise the patent application will be withdrawn after the time. Withdrawing a patent gives up the priority of the filing date, which is extremely unfavorable to protection.
From patent protection or certificate, it is better to hand it in as early as possible. Now, the technology is changing rapidly. It is also possible that your patent was creative three years ago and will become ubiquitous technology three years later. Maybe someone else has applied for the same or similar patent as you.
The entity review fee will not be made public until it is paid. Did you entrust an agency to handle it, then did the agency make an advance or something else happened?
Where the applicant requests substantive examination, it shall submit a request for substantive examination and pay the substantive examination fee. The time limit for paying the substantive examination fee is three years from the date of application (if there is a priority requirement, from the earliest priority date). If it is not paid or paid in full within the prescribed time limit, the patent application shall be deemed to have been withdrawn.
Generally speaking, when applying for a patent, a request for substantive examination will be submitted together. After the state administrative organ accepts your patent application, you can pay the substantive examination fee by adding the application fee.