The "information" the breeders give as a guide for harvest maturity with autoflowers comes from Pixieland, no autos, or rather a very, very rare few plants, ever come close to finishing in the time frames given by the breeders. The breeders must base their times by judging the absolute fastest phenotype, growing in full hydro and with mega watt HID lights and grown by specialized experts in autoflower culture with alien technology, which is a far cry from someone growing in their basement with cheap dirt and a cheap low wattage blurple light.
I personally think the breeeders are doing themselves a disservice with their fanciful timeframes, they should just go by early, mid and late as descriptions, rather than say X amount of weeks and disappoint almost all growers when these times are not met and in about 99.9% of grows. Unfortunately, in advertising "one-up-man-ship", when breeder A says they have a SunsetgorillamintOGgelatocookies strain that is finished in 12 weeks, breeder B then says their SunsetgorillamintOGgelatocookies will take 10 weeks, then breeder C says, then breeder D says......... all the way to BS land and disappointed growers who find that it does not matter which breeder, they all take 16 weeks to be ready for harvest! Anyway........I feel better now for having a rant......
Even outdoors in full sun and with advanced growing techniques, add 2-8 weeks on top of whatever the breeder is quoting and you should be in the ball park.
I have found that late planted photoperiod feminized plants will flower faster, more decisively and out yield any auto flower on the market. They just grow, flower and finish, all within 8-12 weeks pronto, without faffing around, as though they are in a race with the approaching winter, which is essentially what is occurring.
What I regard as late planting outdoors is 4-6 weeks after the summer solstice. As the plants only get days that are getting shorter, they seem to race to finish and due to their smaller size, they don't get root bound or exhausted the soil, if growing in soil, and the quality is exactly the same as earlier started plants.
Autos planted late outdoors will flower while still dwarfish and linger for weeks to maturity and you end up with a few grams due to the short days not providing enough light for the plant to attain a reasonable size, something late planted photoperiod plants will do, up to 3-4 feet quite easily and yield 1-5 ounces, depending on the strain(s) chosen.
In reality, big yield, outdoors, auto flower and late summer, unfortunately are words that do not belong in the same sentence!
Hope this helps, Organoman.