Once you finish The Hotel Assassination, you will get a call from Lester saying that the mansion on 3671 Whispymound Drive is now yours.
The first time that you enter the mansion, you will see that there are boxes filled with Franklin's belongings around the house:
As far as I know, this boxes are gone once you finish the game. Do the boxes get removed as you play the game (15 days in game for example) or after completing certain missions?
Speaking from experience, it seems that the boxes are moved based on mission progression, not time. After moving into the mansion I completed the Kifflom questline as Michael - which takes around a week to finish. After completing this and returning to play as Franklin the boxes still remained.
Referencing the wikia page for the mansion it is verified that the boxes are removed as the missions are completed.
When Franklin moves to this safehouse, several unopened boxes and packages appear. As the storyline progresses, these boxes disappear as Franklin settles in.
