An invention can be marked as patented once you have obtained a patent. It is not mandatory to mark a patented invention as patented but it is advisable to do so. Marking that invention as patented alerts everyone that they cannot legally manufacture, sell, or use the patented invention without permission from you. Anyone who does manufacture, sell, or use an invention protected by a valid patent can be sued by the patent owner for patent infringement.
You can mark your inventions after a patent application has been submitted to the Patent Office of the Canadian Intellectual Property Office, and even before a patent has been issued. In that case, you must not use the word 'patented'. Instead, you can mark the invention with 'patent applied for' or 'patent pending'. Marking your invention that way warns everyone that a patent application has been filed. Everyone is free to lawfully use an invention until a patent is actually issued. If you obtain a patent, however, you may sue anyone who uses the invention while your patent application was pending.
The process of applying for patent protection can be lengthy and complex. Inventors and applicants have varying protections at different stages in the process. Given those complexities, inventors and anyone concerned about infringement of their patents should seek advised from a lawyer with experience in this specialized area or from a registered patent agent.
Canadian Intellectual Property Office
A guide to patents