CoE for dependents

Hey everyone, I'm doctoral student at Nagoya University, just joined a week ago. I need to apply for CoE to bring my husband and 2 kids as dependents. I don't have a part time job at the moment. I want to apply for family's CoE ASAP as my second born is just a few months old. I'm on self funding. My husband will work part time here after coming. My question is: How much minimum balance do I need to show in my Japan's bank account statement to get the CoE application approved?
Also, please tell how much time did it take to get your dependents CoEs?

by ninjamominjapan