When should I apply for a patent to sue the expressway?

For American cases, the timing of filing PPH request is that the substantive examination of American patent application has not yet started. As the US Patent and Trademark Office will not issue a notice of entering the substantive examination stage like China National Intellectual Property Administration, China, the China applicant should file a PPH request as soon as possible. According to the frequently asked questions about PPH from the U.S. Patent and Trademark Office, the common restrictions on singularity in the U.S. patent examination process are not considered as substantive examination notices. In other words, even if the US patent application only receives a restriction/selection request, the China applicant can still submit a PPH request.