Symantec virus definition updates.

I am having an issue with Symantec virus definition updates going out from our Symantec server to client PCs at an inconvienent time. It is interfering with another piece of software that is running on the client pc during the update(which is a different issue). My question is, can the Symantec server be set to send out virus definition updates to client PCs at a specified time, like at 2:00 AM instead of 1:00 PM? Or, at least disallow any contact with the server during production hours? My server admin says that symantec server does not have either of these options. Using Symanec Anti Virus version 10.1
Please help!!
Sean