What i've been doing lately is around 50 days I'll pluck the larger leaves that are closer to the center of the plant. These leaves are usually blocking a bunch of little nugs that haven't gotten much light yet, so they're small, light-colored, fluffy, and immature. Giving them extra light I believe helps them produce larger, darker colored, denser, more mature buds than if I would have left them in the dark until harvesting.
I've noticed that my main cola buds seem to reach their peak size before the smaller ones do as well. I think by the time I remove my larger interior fan leaves, the majority of the growth cycle is done for the majority of the quality parts of the plant, while the parts that were in the shade could still use more growth (and will be allowed to grow because of the light they're now receiving).
I haven't been growing for long, but I've got a system setup where I'm harvesting every 2 weeks, and I'm using 6-8 strains, so I think that's helping (forcing me to) me learn a lot faster than if I were just growing 1 strain without a perpetual setup.
Not the best example, but you can see how I've removed leaves from the yellow picture (~50 days) compared to the normal colored picture (~58 days). I'm trying to get light to hit the buds that were previously shaded. I notice that everything that was previously in the light is now purple, while everything else that was previously shaded is still green.
If I weren't so lazy, I would have removed all of the interior/lower green right after stretch, but I was lazy, so now I'm removing fan leaves @ 50 days instead.