Welcome window to replace the new document window

We need to show a welcome window before creating a new document (or by the choose of the user to create a new document). Would you mind sharing us an example for how to show a welcome window (not a document window) when the app start?
Need this as well. Sometimes the document cannot be created without prior configuration and the user picking a location for it.
Welcome window to replace the new document window
 
 
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