Asking opinions here, preferably with reasoning, o...

You train as long as you need to based off what's happening in front of your eyes, not the internet. For instance in my current grow I tied branches throughout veg but took them off for the stretch(they were beefy limbs and held their shape pretty well) so it wouldn't pull or bite into branches but then I later reapplied some to even the shape back out post stretch. Beware any advice that's linked to a certain 'week of growth'. ANYTHING you do training wise should be linked to your plant's growth and not some imaginary timetable someone makes up. Different strains, even different phenotypes within a strain, grow differently and there's no one size fits all answers to growing- no matter how catchy something read in that 6th grade Physical Science book 40 years ago, biology is a little more nuanced than that. Experiment, learn and have fun with it. Over all my years of growing(yeah I'm old too)one big thing I've learned is it's really hard to screw up so bad you end up with nothing if you're mildly competent, cannabis is a very hardy and resilient plant. In the end you'll become a better grower who can adapt to many situations and environments vs someone who just follows directions. It's like knowing how to bake a cake from scratch vs making a box cake. Both end up as cake but who's really the baker? And what's the box guy gonna do if he's out of mixes and only AP flour instead of cake flour?

There is variation in growth patterns, so there is no 1 answer to that question. I have some seeds from 2 inhouse plants that need to be trained until about 10 days into flower before i let it grow vertically (about as extreme as it gets).. or, i end up with a 3' deep canopy and too much larf at the bottom. Other plants need to be ready at flip to flower in order to give my target of 18-24" deep canopy. Relative to my local environmental factors (lights, climate control et al). This is the best zone of buds for me - YMMV, but the variance in growth patterns are not within our control. You typically want to leave any tie-downs and such until the end. It may seem like it is rigid, but over many weeks it will try to bend back straight, even if slightly it can make the canopy more uneven than it needs to be. I have some plant benders i remove only because the stems will eventually get too thick for them, but then i tie it down with some wire near that bend. A trellis can help too. So it's a total guessing game unless you've grown the plant before (clones)... the stretchy ones can be HST'd if they outpace shorter plants .. the unusually short ones just suck a dick. if you can use a riser for those to keep them even that's great but using something like a trellis can often make that very difficult once the plant has grown into it. don't need 40 years to figure this stuff out :P It ain't rocket science.

you can contiue to lst all the way through flower though because the plant does not grow vertically anymore but what you can do is in a few weeks is try spread the colas out so they get uniform light distribution try ease off on the defoliation because she will stop growing new fans soon and you need them to make buds bigger :) best of luck buddy.

Once you get to about the second week of floweing is when I usually stop unless there are exteme circumstances that force my hand any later than that. By the second week, all goals should have been reached with training and after this, the plant should be left to flower in peace. It is easy for a plant to recover from training during veg, but once flowering starts properly, the flowers should be left alone to do their thing, as it is very hard for plants to "move" their flowers that may be affected during any type of (drastic) training. My opinions are based on forty years of personal cultivation experience and observations and not based on "internet theory". Hope this helps in some way!