When should i begin LST?

My seedling is 3 weeks 3 days old. How much longer until i should begin LST? Pens in pic for size referencing

you want atleast 4-5 nodes before you start training them.... Mine were about 10-12" before i started. ...Be sure not to wait to long though. you can break the stem if it becomes to thick

http://forum.grasscity.com/absolute-beginners/122936-how-lst-low-stress-training.html

Learn young grass hopper