The Mantra can be chanted on any day but one must try to only chant during the Shukla Paksha days. The Mantra has to be chanted at night after 9 pm using a Kamalghatta Rosary facing the east. One must use a yellow velvet Aasan or a yellow silk Aasan. The Verse has to be recited 100 for Malas on that night itself.
Verse: || तां म आवह जातवेदो लक्ष्मीमनपगामिनीम् ।
यस्यां हिरण्यं प्रभूतं गावो दास्योऽश्वान् विन्देयं पूरुषानहम् ।।
Taam Ma Aavaha Jaatavedo Laxmimanapagaaminim |
Yasyaam Hiranyam Prabhutam Gaavo Daasyoshvaan Vindeyam Purushaanaham ||
After the Mantra Japa, keep the Japa Mala under the pillow and immediately go to sleep.
Chamunda or Lakshmi will come in your dreams and tell you something or will only speak. You must at once hear everything and write it down no matter what. Because if you don't you are bound to forget it. I myself have experienced it while trying to do Swapna Siddhi.
Only Kamalghatta Mala can be used and one must light a Pure Ghee Diya in front of Devi and then commence the Mantra Japa.