There's no need to use it at bottling. If you've fermented to dryness, then you don't need it. If there's still some residual sweetness, then sorbate won't stop the fermentation anyway. If you have some residual sweetness and the gravity readings have remained constant for several months then chances are the yeast has done all it can and, again, there's no need for sorbate. I always stabilize after fermentation is complete and prior to back sweetening but long before bottling. If you bottle a mead or wine that hasn't finished fermentation you'll have blown corks, or bottle bombs if using beer bottles.