When Tooltip.Content gets populated?

I need to use the Tooltip.Content information of any given control.

Lets say there is a a control TextBlock and it is bound to a Tooltip. I access the Tooltip of the TextBlock by var toolTip=(ToolTip)TextBlock.ToolTip. The value of toolTip.Content remains null, but if I do a mouse hover over the control it is populated with the desired value.

How do I get the tooltip to populate its content before triggering a mouse over the control? Does the Tooltip loads its content lazily or is there something I am missing?