The cannabinoid levels in cannabis flucuated during flowering... Try harvesting 1/3 of the plant about a week early, Another third a week later and then the last third a week later. This will let you try all the different ripeness..es and it will give light to the little buds under the top buds to grow and swell... If you are talking about using chemicals or something crazy to change the cannabinoid levels then I don't know...