Hey!
Awesome job! Lovely colors! ๐๐
Dark Devil auto are done 8.5 weeks but to be more accurate Iโd use at least a 60x magnifying loupe.
That way you really get in there and examine the trichomes on the buds.
Harvest window opens when you start getting amber pistils(hairs).
Normally when there's 70% amber and 30% white pistils they're ready to start flushing but that's not always the case.
The best way to check is looking at the trichomes.
Clear trichomes haven't reached their full potency, cloudy ones are full of THC and amber are losing THC while gaining CBN.
So depending on your preference whether you want more of a head high or body high.
I normally start to look at trichomes when there are about 50/50% white and amber pistils.
I harvest when after examining and finding 70% cloudy trichomes and 30% amber trichomes.
For me that's a prefect combination, depending on the strain as well.
Have in mind if you use nutrients you'll need to flush the roots, watering only with PHed water or a flushing product for at least a week.
Good luck and happy Growing!