I am thinking of switching my 5 month old coton puppy from Innova puppy food, to the Innova Evo. At what age should I do this? Since it is the same brand food, do you have to switch slowly (over a few days or more?) or just switch cold turkey? Her stools on the Innova puppy food are usually pretty solid, and about twice a day; will the Evo make her have loose more frequent movements? Thanks for your help