Yogurt Mixed with Protein Powder

I like to mix Quest Chocolate milkshake powder into Fage 0% yogurt. But it's a messy process with the one serving containers. Powder everywhere. Any reason NOT to use a large 17oz container and pre-mix it to eat over a few days? It seems like it would also mix together better if it sits for awhile. Has anyone tried this? Want to make sure it doesn't degrade the protein or spoil the yogurt.