It's card to say at this point how far they will go into the books. I have 3 episodes to go for season 4 and they seem to be on track for Baptism of Fire with Geralt and Ciri's storylines. Yennefer's story seemed to be condensed or maybe I'm remembering it differently, but I thought she was missing for most of that book (maybe longer) and the reason for her disappearance was given to another character in the show; in essence their stories were swapped.
Of course they also added in a bunch of the war/politics and revealed some secrets from later books. And a big battle was moved forward to this season too I think.
	
		
			
		
		
	
				
			Of course they also added in a bunch of the war/politics and revealed some secrets from later books. And a big battle was moved forward to this season too I think.