FM milk by right lasts for 2 hours. But I usually feed baby within 1 hour because it will become cold and not fresh anymore.
once touched, at most last 1 hour then must pour away.
if you make milk at 1pm, baby drink at 2.30pm, personally I feel it's already quite late and should finish the milk or discard it.
you should consider the timing passed after making the milk, not after baby first drink it.
there are many cons to drinking cold milk unless you reheat it. I believe reheating causes the loss of nutrients in the formula. besides, leaving milk unfinished encourages the growth of bacteria because the air has germs too