"Afternoon" is translated as "popołudnie" only in certain contexts, such as when it is used as a subject or object. However, when it is used as an adverbial of time, it should be translated as a phrase "po południu" (literally meaning "after the noon") rather than "*popołudniu". So: 'that afternoon was sunny and hot' -> 'tamto popołudnie było słoneczne i gorące", but "we meet this (or: Wednesday) afternoon" is "spotkamy się dziś (we środę) po południu".My try: "Jak(i?) ... w środę popołudniu?"
This is good if, at least, one suggestion has been already given.Thanks! It's to a friend, by email, first suggestion. I think "A co z..." is best. So "A co ze środą popołudniu?"