Hi again
In Portugal is mandatory this information, the ASAE (economic Police) have been take money from all owners of sites, becouse don't have this info in promotion.
Now the code...
go to you theme, and edit you product.tpl on line 275 add the follow code (for presta 1.6)
And add this lines:
Quote{if isset($product->specificPrice.to) && ($product->specificPrice.to|date_format:'%d-%m-%Y' > $smarty.now|date_format:'%d-%m-%Y')}
{l s='Inicio promo: '}<span class="specific_price_to">{$product->specificPrice.from|date_format:'%d-%m-%Y'}</span> </p>
{l s='Fim promo: '}<span class="specific_price_to">{$product->specificPrice.to|date_format:'%d-%m-%Y'}</span>{/if}
After this, when you do a promotion (specific price) on product price the folow dates from specific prices page.
Quote
Inicio promo: 05-07-2020
Fim promo: 06-07-2020