Sugar won't be necessary - the wine yeast will eat all the sugars in there, and your final gravity should be around 0.996 or so. That's bone dry.
Do you want sparkling dry cider? If so, use a priming sugar calculator to figure out how much cane sugar to add. If not, just bottle away once it's crystal clear. I like to bottle after several months, but once you rack off the lees and it's crystal clear, you can bottle. My cider is usually done fermenting after 3-4 weeks, and clear around 2-3 months. But if you can leave it alone for 6 months, you'll be rewarded.
Did you sulfite your cider before adding yeast?