GrowCNanswered grow question 3 years ago I start LST when the plant has at least 3-5 nodes but you can start any time. Earlier the stems are more pliable but with care you can train well into flower. Depending on the strain I start training the main stem when the plant has 3-5 nodes. Then I continue to do more training until about half way through flower. By that point the branches are set in their position and the buds are well established so you shouldn't need to move anything around.
I do minimal defoliation of auto's. They have a limited amount of time and a limited number of leaves. You do not want to cut off solar collectors that fuel the bud making machine. When the plant gets some size I will "neaten up" underneath by removing the lowest leaves that are completely shaded, block my ability to water and block airflow. I do NOT take leaves off the top or middle of the plant unless they are shading a bud site. Even then I prefer to tuck the offending leaf under so the flower can get light.