On day 5, I stirred the starter, discarded half (around 4 ounces), and fed it 1/2 cup all-purpose flour and 1/4 cup filtered water, mixing it up so there was no dry flour left.
Since the (still smelly) starter had slowed way down in terms of activity, I only fed it every 24 hours starting on the fifth day. I also tweaked my measurements slightly based on yet another sourdough starter recipe.