There were some intense discussion on this over at IM. Most guys now go with somewhat less drastic plan. Sodium should be relatively high during your entire contest prep. When you lower carb intake you will flush water much more frequently hence electrolytes. Thus adequate sodium intake is necessary. If this is done consistently through the diet you will not retain any water and be very hard come a few weeks out. All that is necessary is to lower sodium slightly on the friday 24hours out. You can still eat foods with naturally occuring sodium ie eggs. Remember you need sodium to carb up effectively as well. Sodium can be added back into the diet Saturday morning as you are already dry.
P