Write and not worry about scheduling posts, keeping the periodicity for your readers and not waste time finding out next date to publish.
To install it, simply unzip the file linked above and save it in your plugins directory under wp-content. In the plugin manager activate the plugin. Settings can be acessible from WordPress settings menu or even from the plugins administration area.
There you must define which days of week you want to have your posts schedule... and choose a time interval too, if you prefer.
That's all. Now you'll see the plugin scheduled date and time each time you write a new post. Enjoy it!