How you build your plan is dependent on numerous factors—the size and structure of your company, your comfort level with content creation, and the degree to which you are invested in content marketing as a practice.
There's a lot that goes into creating your content schedule, but don't make things more difficult than they need be. Remember the three R's - Refresh, Repurpose, Review - and you will stay in good shape.
Creating best-in-class content is a labor of love. It requires craft, the necessary skills to produce the piece. And it requires graft, the discipline of applying oneself to a project and continuing until the project is complete.