When should I pay the substantive examination fee in the process of applying for a patent for invention?

Substantive examination fee: it can be paid at any time within three years after the application, and it is best to submit the substantive examination request at the same time without waiting for the notice of preliminary examination. In addition, whether to pay the substantive examination fee will start the preliminary examination procedure. As long as the substantive examination fee is not paid, the substantive examination procedure will not be started. Now we can wait for the notice of passing the preliminary examination and the notice of publishing the invention patent.