Usually, new inmates that are not in the general population are awaiting a decision on just where they will place them based upon their criminal history and how crowded the prison is has some factors. If the inmate is low-risk for instance, they might not have a space until someone gets moved so they wouldn't place him in a potentially dangerous situation. Or vise versa. This time period is confusing but it is mainly done to make sure they do not place the inmate in harm's way.
https://www.inmateaid.com/ask-the-inmate/how-long-does-an-inmate-have-to-wait-to-be-placed-in-the-general-population-when-recently-moved-to-the-prison-they-will-serve-their-sentenceout-of-segregation-to-have-normal-visits#answer
Accepted Answer Date Created: June 20,2013