My baby is fully breastfed and I latch her on demand. I feed her roughly every 3 hours except at night where her last feed is around 11pm (she sleeps through the night and wakes up around 7am).
You will know when your baby is full when she shows signs of fullness i.e. hands fall to the side, unlatches, baby appears drowsy and relaxed.
http://babygooroo.com/2014/07/signs-baby-full/