Just be observant for small patches to CSGO as those are the main ones which catch people off guard.
They can be put anywhere from within one week to a year. There is no time span as where VAC is updated. An example was the recent CS:GO Hack that went undetected for 1 week and then a new version was released and after one day it was detected, all due to a 31Mb update.
So be observant and change your hacks after around 3 - 4 of release and you should be "okay" but if you really wanted to keep an account for a long time I'd recommend not hacking.