Vanderhoven7 : The leaders have prematurely seized control for themselves, and consolidated that control.
The Watchtower article "Who Really is the Faithful and Discreet Slave" of July 15, 2013, discusses when the slave is appointed over all the Master's belongings. It says :
It is noteworthy that in Jesus’ illustration, the faithful and discreet slave receives two distinct appointments. The first is over the domestics; the second is over all the master’s belongings ... Note that Jesus makes the second appointment after he arrives and finds that the slave has been “doing so,” that is, faithfully dispensing spiritual food. So there would be an interval between the two appointments.
...
In view of the foregoing, what can we conclude? When Jesus comes for judgment during the great tribulation, he will find that the faithful slave has been loyally dispensing timely spiritual food to the domestics. Jesus will then delight in making the second appointment—over all his belongings. Those who make up the faithful slave will get this appointment when they receive their heavenly reward, becoming corulers with Christ.