It's a judgement call. This happens often. I found some sativa strains still keep on putting out blooms (fresh pistils) even at 14+ weeks of flower. Also, these often do not go amber. So I take them when I get tired of watching them and I want to get the harvest in.
Also, I don't try to go for high % amber. I prefer that the clears have mostly gone cloudy. Of course the plant does what it wants so I'll pick when there are still some clears.