Hi,
In that case, you can create a custom field of the type "advanced date picker" and of the table "product".
Then, in each product you can select a date in that custom field.
And in the settings of your module, you can select that custom field column instead of product_created in the "ordering column".
That way, the ordering will be based on that custom field instead of the created date and you'll be able to adjust it as you want.
You can also edit the created date via mass actions or CSV import, but it's cumbersome compared to that.