Run code in component when document loads with it

Suppose a component was placed in a document, saved and closed. Fresh day, no docs are open. When a document containing the component is opened, I would like to know so I run some specific code in the component.

Component constructors run during plugin load and also during document opening so it is not helpful. The Read function sounded good until I found out that the Instances.ActiveDocument property is null when this method runs.

Is there really no standard way to do that in GH?

Try AddedToDocument(). Just check that the document.Enabled property is false, to avoid the cases when component is added to the document by user later.

public override void AddedToDocument(GH_Document document)
{
     if (document.Enabled == false)
          OnComponentAddedDuringDocumentLoad(); // Your method here
     base.AddedToDocument(document);
}