Beard combs can usually be used after around 3-5 months of beard growth. Until that point, it might be best to use a bristle brush because, in the beginning, the hairs of the beard are going to be quite short. If you find that you need to detangle your facial hair, then a beard comb is definitely something you want to use. When choosing the comb, choose one that is good for the beard length and the thickness of the hair.