Plant training

When do you find is an acceptable age of a plant to start training it for SOG methods?

I just want to make sure I am not stressing a young plant, but also I want to know when I can try and get started to get some diverse growth.

Thanks in advance
~Red~

i have always been at an understanding that you can start training around the 4th interlude, twist ties, clothes line clips is what i have been told to use

Bump bump.

sea of green from seed.I was checking out this koo cheese grow:http://www.greenhouseseeds.nl/shop/index.php?target=topics&topic_id=92