Fran, I'm not really sure ..
But ...
Could it be a light parameter / variable that is often underestimated ?
That kinda belongs to the "Light Quality " characteristics ...
Could it be the " Phytochrome Photostationary State " value of this particular wavelength combo ?
The PPS or also known as PPE ( Phytochrome Photo Equilibrium ) ?
Afterall ,Osram ,launched the new 730 nm ,mainly for fruiting and flowering annuals ...
Could it be ,the "ingredient" that is missing and making all the difference ?
Possibly ...
And please ,do not hurry to turn down another theory / hypothesis ...
Still ,take it with a grain of salt ...
.....
Could it be ,that the reproductive ( flowering ) procedures are related -somehow- to the stem elongation degree and/or
the internodal distance ?
( We pretty much know ,that this is the case with the Ruderalis sp. )
But if the rest types 've indeed evolved from the " ancient" Ruderalis type .....
Can we be 100% sure ,that the actual reproduction of the "modern" Sativa/ Indica species is basedonly on Circadian rythms and not also -to a lesser degree,of course - on stem height (or number of nodes ) and /or internodal distance ? *****
Afterall ,primordia (" pre-flowers" ) usually appear on certain nodes ( 10th - 14th ) ...
Moreover ,phytochrome seems to affect directly, both the flowering and the stem elongation/ internodal distance ...
Dunno ..
Then again ,maybe it's just me, being soooo high ...( As usual ) ...
..........
Nevertheless ,indeed PSUAGRO proves once more ,that above his equipment ,
he has all the growing skills & experties of an excellent and experienced grower ....
..
Having them though ,is one thing ...
Sharing them ,is another ....
....
And just for the latter alone ,he deserves a whole ton of pure RESPECT from the rest of us....
Cheers.
*****
- Maybe ,just maybe ,the number of nodes and/or internodal distances ,serve as a "memory bank" ,
where the " past " states of Pfr/Pr ratios are being "recorded" ,somehow ...
I.e. Auxins or other reproduction-related phytohormones have to "travel " longer or shorter distances to the plant tops and/or "split" their total concentration into more or less branches (nodes ) ,thus affecting the actual time and vigor of reproduction....
Just a "rough " ,but " simple" enough hypothesis there ... -
........
(...) Auxins were the first of the major plant hormones to be discovered. They derive their name from the Greek word αυξειν (auxein - "to grow/increase"). Auxin (namely IAA) is present in all parts of a plant, although in very different concentrations. The concentration in each position is crucial developmental information, so it is subject to tight regulation through both metabolism and transport. The result is the auxin creates "patterns" of auxin concentration maxima and minima in the plant body, which in turn guide further development of respective cells, and ultimately of the plant as a whole.
The (dynamic and environment responsive) pattern of auxin distribution within the plant is a key factor for plant growth, its reaction to its environment, and specifically for development of plant organs[4][5] (such as leaves or flowers). It is achieved through very complex and well coordinated active transport of auxin molecules from cell to cell throughout the plant body — by the so-called polar auxin transport.[4] Thus, a plant can (as a whole) react to external conditions and adjust to them, without requiring a nervous system. Auxins typically act in concert with, or in opposition to, other plant hormones. For example, the ratio of auxin to cytokinin in certain plant tissues determines initiation of root versus shoot buds.
(...)
https://en.wikipedia.org/wiki/Auxin
. I'm pretty sure I started flowering mine after yours and both my Goji and Critical M are catching up to yours. Can you sacrifice one to the god of bottled nutes to see if your vegan mix isn't up to snuff? I mean what can it be? It ain't excessive nitrogen or temps delaying flowering, right? The panel's driver hasn't dropped a few hundred mA, right? I guess I see some heat/light stress in some photos but again they look nice and healthy. Maybe it's temp flux? I was running my AC last night and now I'm ready to plug in a heater tonight. Do you have a new toy in the flowering area? And how much and how long have you been L+HSTing them? That's gotta slow flowering with most strains.
... And I don't think I've read it anywhere but I've come to understand the beginning of flowering to be between showing pre-flowers and alternative branching patterns. I believe around day 28 is when you say they are girls so if you were going off of what I said you'd only be around day 30 of flowering. 
