How to set a starting point when the parenting of objects should start How can i set a starting point when a object start´s it parenting relation with an object . 
Imagine a scenario where a hand takes a glass and lifts it of a table .
to make this in blender i want that the hand that goes down, not being locked to an empty in the glass, but when the hand touchess the glass and lifts the glass i want that in that moment the parent relation with the glass starts and the hand will then smoothly lift the class. 
Is there a way to set when the parenting begins so that it begins at the point i my self decide .
Child of constraint





It behaves in a similar fashion to parent.  You can move the [child] or the target parent. By having a total of two constraints, one for each hand, you could move the glass from hand to hand.  Set keyframes to control start and 
finish of control.  Of course employing paths will bring smooth motion.