I have the HN's available to chicks right off the bat, but they really aren't strong enough to depress the pin until a couple weeks old.
I've had all age birds either pick it right up within an hour...and others that take weeks to really figure it out.
Here's my thoughts on 'nipple training'...
I keep feed and water in the coop because:
-My run is not weather proof, nor totally predator proof.
-We get some wicked weather, wild wind and feet of snow, there can be days on end that they don't spend much time outside.
-I use early morning supplemental lighting and they need to eat and...