2-3 days, once in the mailroom it's up to the staff to hand it out at mail call, usually the same day it's received.
https://www.inmateaid.com/ask-the-inmate/i-just-wrote-a-letter-to-my-son-on-here-how-long-will-it-take-for-him-to-receive-it-his-is-fci-terre-haute-sattelite-prison-camp#answer
Accepted Answer Date Created: October 09,2019