When to put seedlings in fence posts?

First time NFT fence post set up. I have seedlings in rockwool and at a week old. When is it of to drop them into sprayer set up?

As soon as you have roots showing and new growth they should be okay.

Had same ? about a month ago... I just got the Aeroflo2 and my seeds had small set of leaves with taproot maybe an inch out of the bottom of Rapid Rooters... the now look fucking amazing!!!