Why does it take some time for an SEO strategy to work?
SEO success takes time because there is no longer an easy way to trick the system. Search algorithms have become more advanced with an emphasis on delivering the most relevant and highest quality content to their users, based on their search terms.
Previously, to be successful in search engine optimization, it was enough to fill the page with the desired keyword and use as many links to it as possible. This way you would get very fast results. Today, things have changed drastically, and applying such a strategy would do more harm than good.