It varies with different strains with indicas turning sooner and sativas turning later but AI is a heavy indica.
Your plants also look amazingly like mine in structure in places but mine are also an odd cross.
Really it comes down to preference. You want it a little more stoney and sleep inducing then wait a little longer and harvest after there are anywhere from 30-50% ambers. Most people don't like going past that.
You want it a little more energetic and cerebral then harvest when ambers are only in the 5-15% range and the rest are all cloudy.
In the end an indica will tend to be stonier and a sativa will tend to be more cerebral but people seem to like to harvest indicas a little sooner to keep their natural stoniness from being too much and harvest sativas later to keep their head effects from being too unbalanced and rushed.
With that AI I would suspect you should be getting ready to see perfectly ripe trich conditions somewhere in the 8-9 week range of flowering.
Harvesting before the trichs even start turning cloudy will result in subpar smoke that will have much lower THC and terpene content as well as tend to be a rushy/panicky high compared to the finished product.
Personally I'd wait until I saw around 10-15% amber and the rest 95%+ cloudy before harvesting that strain but that's just me.
One last note...Trichs can turn cloudy but the plant have a little ways to go yet and potency to gain. Trichs actually go through many phases as they grow but at the end they turn cloudy before swelling up at the top like a little mushroom. During that swell they increase greatly in potency and
terpenes.
So as a rule of thumb you should always wait for some amber to appear to let you know that the cloudy trichs are actually mature. Unless you want to read up on and keep track of trichs very closely with a pretty decent magnification. Not really required. Just aim for 5-15% ambers with an indica and you can't tend to go wrong.
