Lmao the same time as all babies it tKes a few weeks, months some even a few years to be the color they will be for life lol there's no difference really in the time biracial or African American or white or other babies get their color depending on which parents genes are most dominant will determine if they are lighter or darker so if you are wondering is she gonna get dark brown probably not because you would already see some darker brown on her ears βΊοΈ