Terry51,
When the specific gravity is down to 0.996 or lower, measure it on the next day to see if there is any movement. If it's still 0.996, your fermentation is as done as it's going to get. Thanks to a lack of food and a highly toxic environment, yeast won't keep on fermenting that which is not there. When the sugar is gone, their food is gone, so there's not much left for them to do except release harmful stress chemicals that will make your wine less than pleasant.
The specific gravity measurement should always be your guide instead of time recommendations of the kit instructions. The instructions are written with time guideliness, but not time requirements when it comes to fermentation. The yeast, however, will work at their pace given their environmental conditions and will convert your grape juice into wine. When the wine is dry, all the food is gone, so the yeast aren't actively needed anymore.
If you are going to let that wine sit in a carboy for a while before taking it to a bottle, then you can follow some of the instructions to the previous posts on this topic. The most important thing is to protect your wine from spoilage through the use of sulfites - add 1/4 tsp. of K-Meta to your kit every two months that it is bulk aging (per Matteo's updated information at Winestock 2009). Also, remember to add your K-Sorbate right before you bottle and your clarifiers (if you are using them) about a week before bottling after you are done bulk aging.
- Jim