LST will not alter a plants genetics, which is what controls growth and maturation.
Poor/inadequate lighting is the biggest cause of slow development, followed by too cool temps.
High stress training, such as topping will cause a slight delay in life cycle length, but not normal training such as tying down branches.
The pictures in your diary show that the light is very far away from the plants, a possible cause, but generally it is poor genetics.
The times given by the breeders are quite fanciful and generally based on the best examples, grown under the best conditions, by professional growers and is a far cry from someone growing in their basement using a cheap blurple light.
Every auto I ever grew took 3-6 weeks longer than suggested by the breeders, even under ideal circumstances and with 35+ years of cultivation knowledge.
Sweet Seeds seemed to offer the most reliable and stable genetics of all the breeders I tried, before giving autos up for infinitely superior photoperiod plants which offer much, much better yields and general reults, especially genetic stability. For me it is autos never again, they just don't offer any advantages that I can make sense out of. Unless you are not able to reprogram a timer!
If you check most of the diaries with 8 week cycles they are using big, big lighting. they key to achieving rapid outcomes.
Hoope this helps, Organoman.