Devtard

This plugin overrides default date and time of edited posts with dynamically calculated custom values. This is useful especially when scheduling posts; the plugin can, for example, automatically generate new post dates by incrementing the current most future post date by a specified number of days.
Calculated custom date and time will automatically replace default values after clicking the “Edit” link next to “Publish immediately” in the post editor’s Publish module.
<h4>Features</h4>
<ul>
<li>Date/time values usable as a reference: current date/time, oldest or most future post date/time; specific time of day</li>
<li>Date/time of reference can be increased or decreased by a specific number of days/minutes</li>
<li>Configurable post types and statuses of analyzed and affected posts</li>
</ul>
See <a href="https://wordpress.org/plugins/automatic-post-date-filler/screenshots/" rel="ugc">Screenshots</a> for more information.

Automatic Post Date Filler

Automatically sets custom date and time when editing posts.

timlinden

Remembering to post every day, and which days you already posted, is super easy with this plugin. 
It shows you a calendar with days red when there isn’t a post, and days green when there is. Green 
days you can hover over and see the title of the post, and click to edit the post for that day.

wpFutureCal

A simple calendar that displays when you edit posts, showing which days you have posted on.

Automatic Post Date Filler vs wpFutureCal