At what age does the white coating on the tongue pass?

At what age does the white coating on the tongue pass? The pediatrician said for prevention, wipe it with baking soda when a month old, then at two when we went ourselves and I asked another pediatrician this question, her answer was "don't ask about everything", because I started asking about vaccinations and all sorts of things, who else should ask like not to a doctor? When you wipe it off, does it go away immediately? We only have a white coating on the tongue, ugh. But still think a lot.