I'd wait till it stops fermenting. I've had ferments go for a couple of weeks depending on the strain/temperature. Basically, if it's still fermenting, you know the gravity is still dropping.
I think that you can take a reading just to see how much the brew has progressed and there is no visible activity. If you don't have a 2nd container then I would leave it in there another 8-10 days and think about bottling it then.
If it has stopped bubbling then you can check it. Check it again in a couple of days and if it isn't dropping then you can bottle. However, as the guys have mentioned, it will improve a bit if you can let it sit another 7-10 days.