I'm often asked by clients, "When will my patent application publish?" Whilst the correct answer is "on or just after 18 months from the earliest priority date," this does not provide a specific date. This is because each patent office has their own publication schedule.
For example, the UK Intellectual Property Office provides an advanced written warning of the publication date, which is usually a Wednesday. The European Patent Office also provides an advanced warning and also publishes European patent applications each Wednesday.
For PCT applications, the situation is less predictable as no advance warning of publication is provided. However, WIPO usually publish PCT applications on Thursdays. Therefore, if it is just over 18 months from your priority or filing date and your application has not yet published, then you need to watch WIPO's publication server or Espacenet (http://worldwide.espacenet.com/) each Thursday until it publishes. There can sometimes be a delay of two or three weeks after the 18 month period expires. This can be important if you need to protect new developments with a subsequent patent application outside of your priority year but don't want your earlier application to be citeable as prior art (at least for obviousness in Europe). If you file a new application on the same day as publication then your earlier published application won’t be citeable against the newly filed UK or European patent application.
However, for one week this coming September, please be aware that unusually, WIPO will publish PCT applications on a Friday (7 September 2018).
Changes to the PCT Publication Schedule Publication of 7 September 2018 Due to the fact that Thursday, 6 September 2018, will be a non working day at WIPO, the PCT applications (as well as any Official Notices (PCT Gazette)) which would normally have been published on that day will be published on Friday, 7 September 2018.