I couldn't find a definitive answer. But what I was able to find is the synchronization ticks of every time there is a change to the existing app or a new app is created or a rule is created/ updated.
There is no way to monitor the progress of sync and depending on the number of apps, size of the apps, version of your Qlik it could take a while until your apps are completely synchronized to the nodes.
Any disruption to the apps (network drop etc) midway during synchronization could potentially corrupt your app.
As a general rule I wait 5-10 mins until I expect myapps to be synchronized.
Hope this helps.