Symantec virus definition updates - Primary server to secondary servers

Currently we are running Symantec CE 10.1.4.4000 in our environment.  We have one primary server with about 20 secondary servers across the US.  Our primary server is located in the eastern US and the two problem servers are located in the western US.  During a 4 hour period (usually when virus definitions are being pushed) The western location is being hit very hard with over 100mb of data.  We have changed the Server Tuning Options in the SSC console to "Start a rollout every 480 min" from 17 min.  We also set "Virus Definition Manager" for servers to update everyday within 120 min and also to Retry the task within 1 hour of the scheduled time.  In our minds this shouldn't cause any updates during business hours helping to relieve some bandwidth usage on the WAN.  Does anyone have any other suggestions on how to keep the servers from updating during business hours, yet updating daily at the same time.  

Looking at the documentation I do not see anywhere else that we could possibly change settings to keep this from happening.

Also, just a quick question does anyone know what the normal virus definition update size is?

Thanks,
Brandon