There are a couple of attributes that can be used with [show_products] shortcode to filter the output:
Filter products by any date attribute
You can filter the shortcode output by date attribute. Example:
[show_products date="Release Date" recent="20"]
This shortcode will show products that have the Release Date attribute value somewhere between today and 20 days ago.
You can also show future products like that:
[show_products date="Promo Deadline" future="10"]
This will show products that have the Promo Deadline attribute value somewhere between tommorrow and 10 days in the future.