avast has two types of Update, VPS (the virus signatures) and Program updates and they are handled slightly differently but it doesn't matter where you live al are the same.
The VPS updates happen regularly but there is no fixed schedule, usually 4-5 a week, often more frequently, I have had as many as 4 in a day. When you first connect to the Internet avast checks if an update is available. If so depending on your settings it will be downloaded automatically.
You can see the sort of frequency of these
avast! VPS Updates History.
Program updates differ in that once a program update is released, they are scheduled over a 7 day cycle so as to balance the load on the update servers. So not everyone will be trying to download the larger program updates you might be lucky to be at the start of the 7 day program update cycle or a little later.