A system and apparatus for distributing updates to portable computing device are disclosed. A number of portable computing devices to receive update data is determined and a first number of invitations to update are transmitted to a subset of the portable computing devices to receive update data during a first event. Data describing network usage during the first event is received and the available network bandwidth is determined Based on the available network bandwidth, the size of the update data and network speed, a second number of invitations to update for transmission during a second event is determined In one embodiment, the available network bandwidth accounts for a threshold bandwidth and the bandwidth being used. This allows dynamic modification of the number of invitations based on available network bandwidth while allowing bandwidth usage to remain below the threshold bandwidth.