A method and system for establishing group multicast communication, such as PoC multicast communication. Multiple terminals will join a PoC multicast group automatically at some point before the underlying PoC session is being initiated and thus before there is any PoC content for a PoC server to multicast to the group members. Further, this joining process will occur without the PoC multicast channel being listed in the terminals' multicast channel listings. Thereafter, when one of the terminals opts to initiate the PoC session and thus signals to the PoC server, the server will cause the participating terminals to tune to the associated PoC multicast channel for the PoC multicast group that the terminals had already joined. The invention thereby helps to effectively randomize the timing of join-signaling by the various terminals and thus helps to conserve network resources.