Hours which are past midnight are suffixed with next day date. In Panchang day starts and ends with sunrise.
Ayudha Puja falls during Maha Navratri and it is popular only in South India mainly in Karnataka, Tamil Nadu, Andhra Pradesh, Telangana and Kerala. Ayudha Puja is done on Navami Tithi during Navratri. Most of the time, it falls on Maha Navami during Navratri. Ayudha Puja is also known as Shastra Puja and Astra Puja.
Historically Ayudha Puja was meant to worship weapons but in its present form all sort of instruments are worshipped on the very same day. In South India it is a day when craftsmen worship their tools and instruments similar to Vishwakarma Puja in other parts of India.
In its modern form Ayudha Puja has become Vahana Puja when people worship their vehicles including cars, scooters, and motor bikes. During Vahana Puja all sort of vehicles, which are in use, are decorated with vermilion, garlands, mango leaves and banana sapling and worshipped. Most significantly during Vahana Puja a white pumpkin is decorated with vermilion and turmeric and smashed in front of the vehicle as a custom to get rid of all sorts of evils.