Everything from here on out is only a theory of mine, I am not a pro.
To really get a good point of view on it you need to have the same strain over and over again. I have been dealing with a Skunk1 for about 3 years or so with about 12 harvests. The top buds always start to ripen first, indoor and out.
When looking at my trichromes to judge when to pull, I have to have an idea of what I want first. If I want to keep the CBD(CBD has a heavier buzz) levels lower then I pick when pretty much all the trichromes are cloudy, before any ambers are seen. When I want it at peak potency I wait to see just a few amber trichromes on the top more important buds. And if anyone complains that you can not tell because you don't have a device to look close at the trichromes I will tell you to get a microscope for $10 at Radio Shack or something. And if you can't afford it, you can't afford to grow so get a job.