Also, keep in mind your buds should have a good solid feel to them. If you've got a spot where you've been checking them, there going to harden up pretty significantly in the last week or so. That's the other way I try and assess if I'm on track, or not.
Most all ripening happens in the last few days. ie. The last week or so.
I grow a lot of different cultivars, and it's all perpetual for the most part (all in different stages of development) So for me, this is double critical, and believe me when I say, I've made my share of mistakes pulling weed too early. A little early (few days) is fine, IMO. But the peak of ripening is to die for.