That sounds pretty normal. It all depends on the yeast strain, gravity, and fermentation temperatures. Beers can reach their FG in as little as 2 days or as much as 2 weeks. Just a tip...even though you might have reached your FG and fermentation is "done", leave it in your carboy for a minimum of 2 weeks. 3 weeks is my standard for all my beers. This just lets the yeast clean up, your beer will clear, and the flavors will meld.