If you have created drafts, you can see a list of them. To do that:
Click on the Calendar icon on the menu bar on the left, then click on Calendar Planner.
In the upper left corner, above the connected accounts lists, click on 'Drafts'. Click on Drafts on the dropdown menu.
Click on it to see all drafts.
You can open the a post draft, set a scheduled time, comment and manage a post by clicking on the square symbol on the right bottom side of the post draft.