Triming at the right time? Strain Jack Herer

I have been growing Jack Herer by sensi for almost one year now and love every bit of it. I've grown two pheno types now both sativa and now indica witch is northern lights #5 a big yeilding pheno of Jack herer what i'm not sure is how far there going to streach this time since the sativa type streaches much more. This happns as soon as I flower so here's my problem. I want to trim off lower branches as well as anything not getting light like the top canopy. I have a bad ass HPS 1000 by hortolux on a light mover so I can penitrate quite a bit about 18+ inches or so? Any ways I know that idealy I want to trim one week before I flower and that is now. How far into flowering can I trim?

y trim?! y not just tie (GENTLY) the colas or branches a side to open up the canopy??? kinda like this but WAY bigger??.....

I'm dealing with 12 plants in a 10x8 room under one 1000 that's on a light mover. The problem has been the same thing every time and that's. There's these wasted energys and hormones when the top canopy is all big fat buds and under that there stringy light worthless buds. I have been using them to make hash but I've been reading alot about lollypop,scrog,scog and other ways of getting bigger buds and all of them share the same trick wich is cutting the bottom branches and leaf that doesn't get alot of light. In turn the top canopy uses the streangth to produce much bigger buds.