If you go through my older journals, I actually have tips on storing milk
in an entry. The guidelines are flexible, depending on the person. Some people's milk
spoils faster. Mine seemed to be good for a while. If I pumped at night and left it out in the cool room, it was still OK 10-12 hours later. Made night feeds easier!
We relied on the sniff test- as long as it didn't smell like rotten milk, it was good to serve. Also, my LC assured me that a baby would not drink spoiled milk.