Public use of your trademark in Canada starts to create or crystallize common-law rights in the brand that you are choosing to use. Filing a trademark application in the Canadian trademark office will formalize your rights in your mark. There is a benefit to filing your trademark application sooner rather than later in so far as it will create public notice of your intention and claimed rights in the trademark, as well as potentially creating a bar in the trademark registry to a third party who wished to adopt a similar trademark in your channel of trade in the future.