To put things under proportion, if you have "some" internet connection, usually it would be better for you to download from the avast GUI itself, rather than downloading the full VPS. Here is why:
_ Full VPS update: between 31 and 50 MB (it varies).
_ Each partial update (using avast built in update) is usually between 10KB and 400KB. There are (VERY infrequent) exceptions, where the full VPS update is downloaded again.
So for low bandwith or wherever the download usage is somehow limited, it is still recommended to download partial (normal) updates. You may want to change:
avast main GUI -> settings -> update -> auto-update interval
from 240 minutes to 720 (12 hours), which matches the usual frequency of definitions updates in avast's servers. Of course, this means that you should leave the definitions updates as "automatic".