Here are two phenomenal articles. It is very difficult to find strict science articles on this subject but these two are very accurate and very helpful.
The basic rule of thumb is nothing drastic. If you dont look great one week out, you wont look great at the show. I always refer to the fact that all the water depletion and carb manipulation in the world wont make fat go away. Natural bodybuilders will rarely benefit from water manipulation and when they do it is likely short lived and will usually rebound to disaster. A good carb depletion and a reasonable load will allow the muscle to fill out nicely but should not be over done.
This will be my plan this fall:
Saturday 250 carbs, 2 gallons water
Sunday 200 carbs, 2 gallons water
Monday 100 carbs, 2 gallons water
Tuesday 75 carbs, 2.5 gallons water
Wednesday 50 carbs, 2.5 gallons water
Thursday 300 carbs, 2 gallons water
Friday 400 carbs, 1 gallon water
Saturday 250 carbs before pre-judging, sip water to quench thirst
It depends on how a certain individual responds to carbs but based on my experience, I think this will work well for me BUT, I also plan on being sliced at least a week out.