I don't know about that, usually you would want to harvest based on trichomes, if you have a microscopic lense to analyze it you want to look got a ratio of about:
Sativa:
5 to 10% clear trichomes
60 to 90% milky trichomes
5 to 15% amber trichomes
Indica:
0 to 5% clear trichomes
5 to 30% milky trichomes
60 to 80% amber trichomes
Depends on what ur after, going for the first profile on a sativa gives it some synergy, going for the same profile on a indica gives it a wider spectrum of effects but that do not have as much synergy, and the other way around aswell.
If u can't analyze trichomes, wait untill she starts looking more amber/ish and it should be enough to guarantee you get good stash.