noooo.. that isn't exactly correct...IME. nor is it what I said.
I said by the 3rd week of sept.(12/12 naturaly) that they are 'nearing' maturity. And that 12/12 has nothing to do with flowering in nature.
Your plants will start flowering "around" early/mid to late August
strain dependant. "earl/mid August untill the 3rd week of Sept., is 5-6 weeks on my calendar. And nearing maturity IMO.
Taking clones from under 24/0 and putting them out June 1, "seems" IME, to induce flowering a little sooner, and in turn, they mature a little sooner. Some being ready to harvest by the last week of Sept.
I've been at this for awhile OD. I can only give you the time lines of "my" experience year after year, for "my" area. Let's call it the 35th parallel. Further north, things sgould happen a few days earlier/sooner. Further south, a few days later/slower. But as a "general" time line, I know, I've watched them for decades.
I've had strains/plants finish by late september, while other can run into late October. And there are sat' dom strains that "I" can't finish in my aea, due to imminent frosts/freezes in late October. But I never recall having a plant "not" in full flower by the last week of August, a full 3 weeks+ prior to 12/12 in nature.