Ensure property initialization order of QML item

[Creaperdown]

Hey, I have a custom qml item that is initialized when a certain property is initialized, so I have

Page
{
    id: page
    document: somewhere.myDocument
}

And after that, the page is ready to use, since the c++ functions backing it (e.g. implicitWidth) are relying on document to exist. Is there any way to enforce document being initialized first, before any of the page functionality is called?