I just inserted a pair of front forks and faced the same question.
You will want the clamp to completely hold the fork tube, so don't go lower than flush with the top of the clamp and the top of the tube.
Also, the top of the tube will have a millimeter of so of chamfer or radius. So I put the chamfer distance above the top of the top clamp. So in brief, the tubes were about a millimeter proud of the top surface of the upper triple clamp. More later, Don