I need to know when i can cut the top of my plants to get 2 colas :) and not 1 :)

plz do some one know when i can cut the top of to get 2 colas:)

how big and old do they need to be ?
and when can i start pinching ?
all thos thing :) how old do the plant need to be before ?

im a noob and need advice ?:thumbsup:

http://boards.cannabis.com/grow-faqs...made-easy.html

I top the third node and once again two more nodes on each branch. Yut, when they're little.

thx for the help man :)