Although there is no fixed time, you must invest a minimum of one hour each week for every digital marketing or SEO strategy that your campaign plans to focus on. The exact number of hours that should be invested each month largely varies from business to business. SEO is not a task of one day. It may take min 3 months to a maximum of 1 year to rank the website. And you must be regular in terms of SEO to sustain the ranking on the first page.