flower does't store stuff. Either something was built/grown or it wasn't in the flower. Shouldn't make a difference as it won't impact how flowers ripen or 'grow' - any sort of molecule production related to the flower itself.
more light might help. don't exceed typical DLI your plant can handle though. So, even that is not going to help much, if at all. too much is still too much, in regard to light. So, this would only help if your light is underpowered and 1-2 days of slightly extra light, and only if it's a shitty light to start, at very end will have very limited effect.
"Keep it simple, stupid" = KISS Principle. Stick to it for best results.
The "green light" thing is a myth. they proved that green light actually causes a hormonal response at lower levels than other wavelengths - if anything, green light is worse during dark hours than any other wavelength, lol.. That shows you how retarded bro-science can be... they repeat nonsense over and over again until it is believed to be true by enough people to perpetuate a total myth. Just don't interrupt the dark cycle. (KISS Principle, again) ... If you do over a couple days at the very end, that likely cannot cause any negative repercussion, but still easily avoided.. don't harvest during dark cycle, lol. KISS!
Definitely harvest with light on... Don't overthink this. 80-100 days invested. 1-2% max effect and that's reduced further as whatever you do is not 100% of the pie. Fretting over fractions of a percent of what amounts to your outcomes. don't lose sleep over or invest too much effort/resources for .1% or less.