Ok momlife here a question it hot today n my son like drinking whole milk when cold idk if should…

Ok momlife here a question it hot today n my son like drinking whole milk when cold idk if should have cold or not he dose injoy it n i only warm up at NIGHT get him sleep faster n more how long do leave out a milk if you don't finish it because i know formula tell you no good after one hour how about milk dose anyone ever think about that lol