What exactly are you trying to achieve? Are you trying to build a directory structure on the device? If so, that won't help if you are using the Kobo software to read the book. It doesn't use the directory structure in the interface. If you are using KOReader or Plato or something else, it might work.
For reading in the Kobo, you could create a collection for each day. When you have read all the new articles, you can remove the collection.
You could do this with a custom column with the template:
Code:
program:
news_date = format_date(raw_field('timestamp'),'yyyy-MM-dd');
contains(field('authors'), 'calibre', news_date, '');
I'm assuming that "calibre" is the author for the news articles. But, you can use whatever other test would be appropriate.
If you do the above, you would add the column the the "Collections columns" in the driver configuration. That should create collections for each day as you send the news articles to the device.