I mix goats milk with neocate and I make it 50/50. I make 24 oz and it usually lasts me 24 hrs, sometimes less, I usually make it in the evening for the next day. I have never had any problems thus far.
Since I use powdered of everything, I will mix it all together and then just add the water when I’m ready to use. I do that for anyone who keeps Owen for extended periods. I’m sure you probably use RTF for everything, so I’m not sure what to tell you. Sounds fine to me though.
At first I would always taste the milk before I gave it too him b/c I was paranoid about it “spoiling” or getting rotten. Now, I know it’s okay for 24 hrs at least. I’ve never went longer than 24hrs though before making new.