LST

btw, a little more intense light will thicken up that stem and stop stretch. slowly step it up, if not already.

When it can handle the stress and is large enough to make it worth while. This depends entirely on your intentions... how big is it going to grow? If you only need ~4 vertical shoots to fill the space, i'd start LST with 4-6 nodes. Often anything under the bend need to be pruned off. I also want a little growth from those axillary buds before i do it. So, in this context when i see 4 fairly well-growing buds i'll top above that point, prune off anything below initial bend in apical meristem. Other thing to consider is direction you bend it. Some bend it so 1 side is facing upward and prune off stuff facing down. Or, you can bend 45-degrees between axillary growth and each will have a chance to grow vertically. You'll often have to thin this out a bit along the spine, but will have more options for bending and filling space with both sides of plant with equal ability to grow north. Use an anchor in opposite direction of where you bend the plant. This reduces stress on roots... if those rip, your plant will look ugly for a long time after bending it over. Also, bend and shape the plant before tying anything down. If the ties only resists hydrostatic pressure, again, much less stress on roots, and easier to shape it this way too. Ties / restrains merely retain shape you make. The more even / level it is where the axillary growth is, the more even the grwoth will be of all those branches... height is key too. If any are taller, simply bend them down for a few days while the others catch up, then let them go. They'll spruce back up quickly. Topping a taller growth can also even things out... even if oyu don't want 2 colas from 1 branch.. can remove that other cola if too dense and merely keep them all the same size. This will make a diffeerence in how resources are distributed for flower production... The more even everything is, the more even the buds will be. Avoids big chunky ones that'll be high risk for mold and small scraggly ones you don't want to smoke.