"Little Things" has been released in Butcher's Dresden anthology Heroic Hearts. When does it take place?
Assuming that indeed you are talking about the "Little things" short story, then the key to place it in the timeline is in the second paragraph:
In the days since my lord had defeated a mad goddess in single combat and claimed his Castle as reward, pizza deliveries had been spotty. The troops had begun to express concern. They had, after all, fought for their right to pizza. Castle stores of inferior frozen stuff could only last so long.
Those events have taken place in the "Battle Ground" novel - currently (as at May 2022) the latest full novel in the "Dresden Files", so "Little things" must take place some time after, but hard to guess how much time has passed, but definitely less than a year, since Harry has been obliged to do something significant exactly one year after the Battle, which would be definitely mentioned.
There was a dark mortal entity my lord called a conomee. The conomee was very bad, because of all the rubble and the blocked streets after the Battle. Battles make conomees that were once good very bad. Now the bad conomee was preventing pizza from being delivered.
The fact that he is still depressed (and the bad "conomee") suggests that a relatively short time has passed - in the Christmas Eve (which takes place obviously during Christmas the same year as the battle) he seems to be more at peace.