Event when resources of page are loaded in WinRT
What event are start when resources of page are loaded? (Resources like localization's strings)
In the constructor you get an InitializeComponent() call which loads the stuff in your XAML, where the resources are typically added. After that I think you can assume they are loaded. If any of these does some other loading - you might need to wait for it to finish with some targeted code that will depend on the resource you are waiting for.
Note that in UWP apps (Windows 10) - resources are typically lazy-loaded. That is - while the resource may get created when the XAML it's defined in is loaded with say InitializeComponent() - the resources themselves only get constructed when they are first referenced - either with Static/Theme-Resource markup extension or from code behind by accessing them with the resource dictionary's indexer. Also note that the resources in App.xaml get created once for each application window even though there may be only a single Application class instance, since different windows use separate dispatchers.