P226:5, 20:4.1 Prior to the planetary appearance of a bestowal Son, an inhabited world is usually visited by a Paradise Avonal on a magisterial mission. If it is an initial magisterial visitation, the Avonal is always incarnated as a material being. He appears on the planet of assignment as a full-fledged male of the mortal races, a being fully visible to, and in physical contact with, the mortal creatures of his day and generation. Throughout a magisterial incarnation the connection of the Avonal Son with the local and the universal spiritual forces is complete and unbroken.
P226:6, 20:4.2 A planet may experience many magisterial visitations both before and after the appearance of a bestowal Son. It may be visited many times by the same or other Avonals, acting as dispensational adjudicators, but such technical missions of judgment are neither bestowal nor magisterial, and the Avonals are never incarnated at such times. Even when a planet is blessed with repeated magisterial missions, the Avonals do not always submit to mortal incarnation; and when they do serve in the likeness of mortal flesh, they always appear as adult beings of the realm; they are not born of woman.
P227:1, 20:4.3 When incarnated on either bestowal or magisterial missions, the Paradise Sons have experienced Adjusters, and these Adjusters are different for each incarnation. The Adjusters that occupy the minds of the incarnated Sons of God can never hope for personality through fusion with the human-divine beings of their indwelling, but they are often personalized by fiat of the Universal Father. Such Adjusters form the supreme Divinington council of direction for the administration, identification, and dispatch of Mystery Monitors to the inhabited realms. They also receive and accredit Adjusters on their return to the "bosom of the Father" upon the mortal dissolution of their earthly tabernacles. In this way the faithful Adjusters of the world judges become the exalted chiefs of their kind.
P227:2, 20:4.4 Urantia has never been host to an Avonal Son on a magisterial mission. Had Urantia followed the general plan of inhabited worlds, it would have been blessed with a magisterial mission sometime between the days of Adam and the bestowal of Christ Michael. But the regular sequence of Paradise Sons on your planet was wholly deranged by the appearance of your Creator Son on his terminal bestowal nineteen hundred years ago.
P227:3, 20:4.5 Urantia may yet be visited by an Avonal commissioned to incarnate on a magisterial mission, but regarding the future appearance of Paradise Sons, not even "the angels in heaven know the time or manner of such visitations," for a Michael-bestowal world becomes the individual and personal ward of a Master Son and, as such, is wholly subject to his own plans and rulings. And with your world, this is further complicated by Michael's promise to return. Regardless of the misunderstandings about the Urantian sojourn of Michael of Nebadon, one thing is certainly authentic -- his promise to come back to your world. In view of this prospect, only time can reveal the future order of the visitations of the Paradise Sons of God on Urantia.