Trade Marks Act 1994 s.38(2); TM Rules 2008 r.17 gives two months from publication in the Trade Marks Journal. An extension can take that to 3 months, but it has to be asked for — work to the base date.
The application is examined first, then published. The clock starts at publication. Counting from the filing date makes you early, which is harmless; counting from registration makes you late, which is not.
The UK opens the window at publication of the application, as most offices do. But Switzerland, Germany, Japan and Sweden register the mark first and run opposition from publication of the registration.
Applying one office’s rule to another does not shift a deadline by a few days. It invents one that never existed — and the real one may already have closed.
Once opposition lapses you are into cancellation or invalidity — a different action, different evidence, more cost, lower odds. Worth knowing early: a holder whose own book is largely lapsed or withdrawn is more vulnerable to a non-use challenge than the register first suggests.
Read from the public registers and the cited provision. Intelligence, not legal advice — your counsel confirms the date and acts on it.