Om Swami
Can meditation or chanting help when I have depression and my mind won't calm down?
A little practice each day, in a form that suits you
Sitting quietly and trying to calm the mind can sometimes make it agitated beyond bearing, so there is no rule of thumb. Even a little a day adds up, whether it is chanting, meditation, reflecting on a scripture or a ritual.
If they can do even a little bit a day it will all add up, whether that is chanting, meditation, reflecting on a scripture, or even a yagna or a ritual of some kind.