How to detect Aplication.Init completion


Is there any way to detect that Init method of the Application class has been completed? IDK maybe to add some listener, maybe to use some servlet filter?
Why I am asking is bcoz I need to call some external function on the start of the application and check if it was opened from the “active” node in my system. If not, then I should show some notification and redirect to the right node. Using setLogoutURL\close technique I cannot do this before Init method completes, and I need to call my external function before webuser can interact with controls.