In order to target the date, separately from the rest of the content in that box, you need to segment it with a HTML tag e.g. a span. The span doesn’t need a class or id, although you can add one. Text nodes like that date do need to be wrapped with something in order to be targeted with CSS though.
P.S. ::before and ::after are separate “pseudo” elements created with CSS, they cannot be used to target text nodes present in the HTML.