Faelivrin and I spent some time working out the genetics of elven hair color, and how those traits would be passed through families. Certainly, red hair is meant to be just like humans - a simple recessive trait that can skip generations and is not overly common. The only individuals with red hair called out by Tolkien are Mahtan and 3 of his grandsons (Maedhros, Amrod, and Amras). So, among the Noldor at least, red hair seems to be rather rare (but hardly unheard of).
We could make red hair common among the Falathrim, to visually distinguish them from other groups of elves. After all, there's so little known about them, that there is no reason that *couldn't* be true! Just as easily, the silver/white hair could be confined to Doriath, and the Falathrim could all be dark haired. In general, the Sindar are majority dark-haired, with certain families having blond or silver hair. Silver hair does *not* appear to be like in humans, in that it is not linked to old age, but a natural hair color elves can be born with. We modeled the genetics off horses, where white/silver can be a natural hair color. But even in horses, white is also linked with old age.
So, I am very much fine with Círdan having long white hair and a long white beard in the 3rd age, and showing different hair colors earlier. But, I also think that *only* Círdan should have the 'going white' age effect. Celeborn is silver-haired from the beginning. Elwë, Olwë, Celeborn, Nimloth, Earwen, and Míriel all have natural silver (or white) hair, from a young age. Thranduil is blond. Círdan has no known relatives, and therefore linking him to anyone else via family trees is impossible - so if he's a genetic anomaly, he doesn't impact anyone else.
I think we do need to show Círdan aging. We went back and forth on whether he'd have a beard yet in the beginning - I think not. I think he should be a regular beardless elf until after the end of the First Age. Dealing with his aging can be part of the 2nd Age storyline. We also don't want Círdan and Mahtan to be mixed up by the audience, so linking beard and red hair might be a bad choice. Mahtan should be the only bearded elf in Season 2.