The earlier that they are pinioned the better. However, regardless of their age, if the cygnets are more than 1-3 weeks of age, the pinioning will have to be conducted under anesthesia. So, the earlier that you can get the procedure conducted, the better. Even though KS may not require pinioning, if the birds get out and start a feral population, then state wildlife officials can kill them. So, it is in the best interest of the birds to keep them in a captive setting in which they were raised and familiar with people and supplemental feeding. The cygnets may also not be street smart to protect themselves from any unfamiliar predators should they leave for another area. The Regal Swan