When does avast release its new updated VPS? Is it best to schedule the task for in the morning or at night?
They do it, when necessary… So the best way is do it automatically… Every hour, twice in an hour or every 20minutes.
It depends on your environment resp. network bandwith 
there is a standard task updating the VPS on the ADNM server.
dont mess with it. Leave it as it is.
Then the clients update as soon as they contact the ADNM after the ADNM has been updated too.
There is no task needed, when you set auto actualization in properties of Computers catalog