Hi, When you doing LST it's very important to Hold some how bottom of the main steam with some stive component, (i'm usuing electric cable 3 x 2,5 and i take wires from inside), bacouse when plant is growing it's can brake the main branch and you can lose all plant.
Here you have schematic Look bue line
https://steemkr.com/cannabis/
@chackett/training-the-plant-your-growing-no-matter-the-strain-or-end-result