Goddess Shailputri Mata is worshiped on the first day of the Navratri (September – October). Shailputri Mantra is chanted on the first day of Navratri and also on all those days by people who prayer to this form of Goddess Shakti. Shailputri Mantra is in Hindi and there are four mantras – Mool Mantra, Dhyan Mantra, Stotra and Kavach Mantra.
Most devotees only chant the Mool Mantra.
A devotee can chant any of the mantras. He can also put them into any combination and chant. Like some people chant Mool and Dhyan or Mool and Kavach.