Thanks for this plugin, sadly I cannot seem to get it to work properly, I might be doing something wrong.
At the moment, no matter what I do, I end up with the "Please wait for 300 seconds to be able to publish this post to the Steem blockchain as there is a 5 minute cooldown." error, even after waiting a full hour.
in the right hand menu this "300 seconds left to do another post action." stays on 300 aswell and simply does not countdown or leave at any time.

As for a possible enhancement on this plugin, I'd love it if it had a "publish old posts" option in which you could specify a schedule or timeframe in which the older posts get auto published to Steemit.
This would greatly improve the value of this plugin to already well established larger wordpress blogs.