At what age do you trim a baby’s fingernails?

Shalom uvrakhah, 

It is permitted to trim a baby’s nails at any age, though some are accustomed not to cut the baby’s fingernails or toenails for the first thirty days (as cited in Nitei Gavriel, Hilchot Niddah, part 3, chapter 64, note 6). It is also not advisable from a medical standpoint — see the website of Sheba Medical Center, which states: It is forbidden to cut a baby’s nails until the age of one month, because before then the nail is thin and soft and is still attached to the skin of the finger. 

Bivrakha, Hillel Meirs