Calves are 5 mo old. Cows getting worn down. I've never used creep feed before. Bought a couple creep feeders, wondering how this works. I've got wagons of 70% cracked corn 25% rolled oats and 6 lbs / bushel 34% baby beef. Do the calves just go free choice at it right away or does there need to be a buildup time? Hate to just dump this out there and get everyone sick.