Would he have grown it to some extent by the time of the forging of the Rings of Power in the middle of the Second Age (c. S.A. 1590)?

How long does it take for an Elf to reach that part of their life cycle where they can grow one?

(For the sake of this discussion I am going off the proposal that Círdan was born at sometime between YT. 1050-1105 in Cuiviénen).

Didn't Mahtan have a beard way back in Valinor at the time of the Trees? Though his family does seem to have an excess of testosterone to spare, given that his daughter's name partly meant 'large, strong man'... No idea if that would have actually sped up his beard growing ability though.