Need Help With Total Lumens and flowering height

I have been growing for years indoors under a 430 HPs and 430 MH conversion in a space 245 sq. ft. I usually grow too many plants for the space, hoping to end up with 8 or so fems. I have always tended to go 12/12 when there are about 4 nodes on my youngest plant. A friend recently suggested I wait until they're a min. of 2 ft before flowering on the theory the light will still penetrate to the bottom of the plant and grow bud. Assuming I'm replacing my bulbs annually, do I actually have enough effective light to reach the bottom branches, and does anyone suggest topping or training to make better use of available light. My inclinination remains to do as I've always done and get the boys out of there asap to make more room for the girls. Sorry if this has been covered relentlessly.

430 penetration wouldnt be effective .stick with what you know

A 430w can support healthy growth about 3' away from the bulb with almost a foot needed between the bulb and the plant tops.

leaves are not as solid as they appear, light passes through them and some hit chloroplasts which interacts with them and causes the whole photosynthesis thing while the remainder continue on and hit the next leaf and so on. it's something like 15% of it that the top leaves can absorb, the rest keeps going. That being said I would say no, not really. if you wait till 2 feet youll end up with some 4-6ft plants and while i love my hps and all its just not that powerful to reach that far down. waiting for A foot tall would be good though imo.

thanks guys/gals. I forgot to mention my friend is an electrician who is probably off the meter w/2000 watts (!!!!!!!!!) in a room perhaps 10 sq ft bigger than mine. I'm sorry, but that is nearly cruelty to vegetation under the Geneva Conventions. What is the min. lu/per/ft to sustain max. growth in the space I described?

I like what all you have said! I should have stated at what height/level would you guys/gals have started flowering given the limited lumen depth of 4300K peak. I think I've got it right! It is rather hard to f/u!