Hi,

First, I would like to say that based on my understanding Navigation is performed on each Region independently. Therefore, it would not be a concrete sequential execution between Navigation on different Regions.

Then, I believe the approach you suggest would work correctly, but it does not seem to be pretty elegant.
However, another approach you could perform would be similar to the following thread's solution:

• Module initialization problem
  

Basically, Registration and initializing of Views/ViewModels should be implemented on Modules Initialization process. Then, in order to be sure that every View would be already instantiated, you could raise a InitializationCompleteEvent at the end of Bootstrapper's run() method, which would be the trigger for parents ViewModels to Publish() the EventAggregator Message for their child Views. You may find detailed information in the above linked discussion thread.

I hope this helped,
Regards.

Gabriel Ostrowsky.
https://blogs.southworks.net/gostrowsky