PieSync will sync any updates or creations it is configured to do within a 5-minute timespan. Once your connection is active, PieSync will continuously monitor the contact data and every 5 minutes, it will sync the changes that took place over to the other app.
If you've just activated PieSync or if you updated your configuration by clicking ‘save and resume syncing’, you might see this icon stating “Scanning your data - this might take some time…”. In that case, it will likely take a little bit longer for PieSync to sync your changes. This is because at that moment PieSync isn’t monitoring your contacts (yet). It is instead scanning all the contacts in both your applications - even if you’ve only chosen to sync a subset. Once the scan is complete, PieSync will start syncing the changes.
Note that the more contacts you have in both your apps, the longer this scanning phase may take, but even with a huge database (100,000+ contacts) it generally shouldn’t take more than three hours to complete. If that’s the case, please contact PieSync Support.
To learn more about the different dashboard states, you can read this article.