don't worry!! if yr baby feel hungry, she will call you up!!
the time is depend on if yr baby is "資油擔定型" or "快速型".
it is lucky if he is "快速型", otherwise, you need more time & patient to feed those "資油擔定型" who would fell to sleep when you feed to him!! Thus, some of mom would choose the "pump" method. However, another result will be caused when you used "pump" - yr baby dislike to 埋身餵!!!