A method of setting up a multicast communication session at an access network within a wireless communications system, comprising: transmitting (725, 925B) an announce message announcing a current multicast communication session to a given group of access terminals within an initial cluster of sectors; after transmitting the announce message, waiting to receive at least one registration request (730, 930B) for the current multicast communication session from at least one access terminal belonging to the given group of access terminals; receiving at least one registration request for the current multicast communication session from at least one access terminal belonging to the given group of access terminals; and after receiving the first of at least one registration request: determining an approximate time difference between the termination of a previous multicast communication session to the given group of access terminals and the setup of the current multicast communication session; and if the approximate time difference is less than a threshold period of time: loading a stored cluster of sectors that supported the previous multicast communication session to the given group of access terminals, and turning on a multicast flow for the current multicast communication session at least within each sector of the stored cluster. transmitting (725, 925B) an announce message announcing a current multicast communication session to a given group of access terminals within an initial cluster of sectors; after transmitting the announce message, waiting to receive at least one registration request (730, 930B) for the current multicast communication session from at least one access terminal belonging to the given group of access terminals; receiving at least one registration request for the current multicast communication session from at least one access terminal belonging to the given group of access terminals; and after receiving the first of at least one registration request: determining an approximate time difference between the termination of a previous multicast communication session to the given group of access terminals and the setup of the current multicast communication session; and if the approximate time difference is less than a threshold period of time: loading a stored cluster of sectors that supported the previous multicast communication session to the given group of access terminals, and turning on a multicast flow for the current multicast communication session at least within each sector of the stored cluster. determining an approximate time difference between the termination of a previous multicast communication session to the given group of access terminals and the setup of the current multicast communication session; and if the approximate time difference is less than a threshold period of time: loading a stored cluster of sectors that supported the previous multicast communication session to the given group of access terminals, and turning on a multicast flow for the current multicast communication session at least within each sector of the stored cluster. loading a stored cluster of sectors that supported the previous multicast communication session to the given group of access terminals, and turning on a multicast flow for the current multicast communication session at least within each sector of the stored cluster.