Have done a quick search but was unable to locate the answer to my query so apologies if the answer is somewhere in here

What age should finch babies (especially Goulds) be before you fit leg rings? A budgie breeder friend says he rings his birds at 9 days of age and thought finches would be a similar age.
Any info appreciated.
This has just given me a thought: Maybe the forum needs a "FAQ Section" to cover newbies like myself
Thanks