Beleriphon
Totally Awesome Pirate Brain
Ciri is suppose to be 12, so the Bards only a decade or so older than when he first appears.
the show runners however did say that child Geralt was taken to become a Witcher 95 years before present and that Yennefer is a couple of decades older
It doesn't hurt that witchers age very slowly (current natural lifespan is unkown, no witcher has ever died of old age), and Geralt more so due to some additional mutations.