That way you don't have to warm the milk
- it's ready to go!
is different, but in general milk
is good at
room temp for at least 5 hours. In the summer when it's warm, it's less- in the winter it's longer. When I pumped for my first, i used to pump before bed, leave it next to me, and feed it to her up to 10 hours later when she woke up. No warming bottles at night :) This was possible because the room was chilly at night.
You can tell if the milk is good by simply sniffing it.