Fastbuds GG autoflower LED grow

Morning buddz! Day 15 of plantlife has begun, she is doing fine under her new light ( 150w more xD ), i hope this will trigger her growth some more! The leaves are aiming for the light, she' s happy. The other plants are purple jalapenos( never smoked one ) and will be in here for a couple of weeks to grow. Watering once in 3 days now i guess, i always look at the soil and plant for this. When is the right time to LST, is it depending on lenght or nodes? Thanks in advance! Edit: plant is looking much better a few days under its new sun, growing alot, more widly than upwards. She did 1.5cm in 3 days, growing taller seems to accelerate but we'll see that in the upcoming week! Have a great one!