Mangla aarti is important because it is first thing in the morning.The Scriptures talk of the "Brahma muhurta" hour. It means one hour and a half before the sun comes up. This time is very auspicious because the sun is pushing all of the energies of the Earth from a sleeping stage to an awakened stage. Similarly it is pushing the mind, the intelligence, and the bodies of all the living entities from a sleeping stage to a higher stage of awakening. Therefore, mangla aarti is calculated to be at that time, and if we give our attention and energy towards glorifying the Lord, it is very beneficial and auspicious to begin the day hearing and chanting about the glories of the Lord.