Katou waited for what felt like eternity after his exchange with Crowley before he wrote to Setsuna and Kira. It only took him a few days to repress the hell out of his feelings get over Crowley, and even shorter to get used to his drugs again, but he still wanted time to just be alone. Now that he was over that too, he wrote his letters.
Kira
You still waiting?
-Katou
Setsuna,
How you feeling? Not still sore, I hope.
-Katou