JavaFX 2.0 :: Invalid Transform On Shape After Creation

I am working on a UI in JavaFX and create several instances of a custom control class. The control consists of a Pane which wraps several other containers, one of which contains a Circle shape.
 
At one point, I instance this control and access the Circle shape directly. I transform it's center coordinates (which are always {0.0, 0.0} ) to Scene coordinates.  The problem is, the transformation always yields coordinates that correspond to the upper left corner of the control's root pane.
 
In other words, it's as if the Circle is positioned at the upper left corner of the custom control (when, in fact, it's positioned near the lower right corner).
 
I have other instanced controls already in the scene, and they do not have this issue - converting the Circle's coordinates to scene coordinates works as it should.
 
It seems obvious that I'm accessing the Circle too soon - that perhaps the scene graph hasn't been fully traversed for the control and the Circle's position within the control's hierarchy hasn't been updated.  I've verified that my attempt to access the Circle's center coordinates occurs after the control's initialize() method is executed, so how to ensure the control's scene graph has been fully updated before I try to manipulate the control...