When is it okay to start flight recall training?

[Pajarita]

This question is addressed to Michael so I will not respond except to say that different species have different behaviors and different ages when they mature.

[Wolf]

In addition to what I have already said in my last post, I would like to add the following thoughts.
Cockatiels are a small and timid bird and as such I think that some of them may not be suited for harness training and some of them may do fine with it. You will need to pay close attention to your bird to know which way to go with this one. They are very flock oriented and are often nervous to the extreme when face with new and unfamiliar things without the mental and emotional support of the rest of the flock. As a general rule it appears to me that they would do much better with being allowed free flight within your room or home or in a large flight cage with one or more of their own kind, always in pairs.
I have to think about some of these birds as I don't have all of the species. I don't have any cockatiels or any of the species that are similar in their behaviors to them. All of mine are either larger, more independent birds or of a much more aggressive species as in the case of my parrotlet.