Aswin Anand

With this plugin, assigning multiple categories to one or more posts is a 
breeze. Pop the plugin’s PHP file to your wordpress plugin directory, 
activate it and click on “Assign Categories” under the Manage menu. 
The page will show the list of available categories, followed by the 
available blog posts. You can select the categories, select the required 
posts and then click on “Assign Categories” at the bottom of the page. 
Now, all your posts will be assigned the new categories.
Plugin Page: <a href="http://www.aswinanand.com/2008/10/bulk-assign-categories-to-multiple-posts/" rel="nofollow ugc">http://www.aswinanand.com/2008/10/bulk-assign-categories-to-multiple-posts/</a>

Assign Categories

Assign one or more categories to multiple posts in a single shot, with or without preserving existing categories.

Landon

Originally adapted from <a href="https://wordpress.org/plugins/scheduled-post-trigger/" rel="ugc">Scheduled Post Trigger</a> to be more resource efficient.
Instead of running a query every time a visitor loads your site, Re-trigger Scheduled Posts runs on an hourly schedule to check if any scheduled posts have been missed. If any scheduled posts have been missed Re-trigger Scheduled Posts publishes them immediately.
There is no configuration required for this plugin to work, just install and activate it and it’ll handle the rest.

Re-trigger Scheduled Posts

Originally adapted from Scheduled Post Trigger to be more resource efficient.

Assign Categories vs Re-trigger Scheduled Posts