How can I determine when all child components have completed OnInitializedAsync()?

I have a dashboard page with 4 - 7 child components (some are not included via @if(...){ ... } if the user is not an admin).

I want to put up a single loading... circle over the entire page while all the child components are loading. The main page has 3 lines of code in its OnInitializedAsync so that is done and returned before the children are even started.

I can give each child an event in the parent to call when they complete OnInitializedAsync and when I receive that event the 4 - 7 times, then hide the loading overlay. But I'm not wild on this approach as it requires I get the count of children execatly right for every combination of user rights on every page. In other words, I'll make a mistake somewhere.

I would also like to use the for my bUnit tests to WaitFor() until the page is fully rendered. But this is a nice to have as in the unit tests I can just wait for the bottom-most element to render.