I think the biggest concept you are missing overall is light penetration.
Flourescent light does not penetrate foliage well at all.
HID lighting does but tall plants indoors are NOT efficient! You said you'd had good luck with a scrog... that whole style is designed so that penetration of light into the plant's foliage is a nonissue, because the plant is PLANAR. a TREE is 3-dimensional, lol... if you are going to use a 150 on her, you have to tilt her on her side and train the branches more into a plane... get it?
The benefit of a big ass light is that it CAN penetrate deeply.
Better yet, a 1000HPS under a 4-foot parabolic... ooooooooh sexy baby!!! THAT'S the way to do it!!!
You should see the bushy lil monsters BlueBear was showing off that he grew under paras. mm mm good.

IMHO at 30 inches if you are going to hemm and haw over whether that plant is ready to flower, you need to get going on tying her down NOW becaue you have already passed the point of no return for an untrained plant indoors. That bitch is gonna double in size, and your little light can NOT effectively illuminate a 60+ inch plant, period.