Roughly...
It depends on lighting, humidity, etc but if you just want a estimate then we must know age. Depending on age less for younger & more for older obviously...I would start off with a cup of water making sure you pour it close to the stem. Then depending on how fast she grows move up to 1.5 cups 2 etc. As they get older you want to make sure the entire surface area of soil is getting a good amount of water as those roots will grow all over if water is poured in more than one area.
p.s If your watering everytime until you see drainage then more than likely your going to be over watering (BAD).