LO is 5 months old and we won't be starting solids until she is 6 months. However, I want to try and start practicing using a sippy cup (either soon or when we start solids, doesn't matter). I'm wondering what to practice with. Pumped milk (isn't it a bit of a waste to pour liquid gold into a sippy cup only to have it spat out or not used)? Water? Do babies need water? Is it too early to use a sippy cup?