Without knowing what you are using, it is kind of hard to find good advice. Is this social media calendar to be posted on social media or on a website? If on a website, is it plain old html or something like WordPress? To set up a useful calendar you will first need to have a set of information, then when we know how and where it is to be implemented you can get suggestions.
For example, it could be posted as an image or as a table or as a script. That decision depends on how and where it is to be implemented and how often it changes.