You're fine, don't worry about it too much. Generally, you want to do a couple days of checking SG. When it doesn't move for a couple days, then you rack/bottle/whatever. As it stands, (as people have said) you might not have enough yeast, which means you'll have residual sugars, which just means it'll be a little sweeter than it should be, and a little less alcoholic. Either way, it will still be beer, and drinkable and awesome.