I like to pull the fawns when they are 6 to 12 hours old after making sure their tummy is tight from mama's first meals. The longer they are with Mom, the harder it will be for them to get started. They have to not only get used to the ''new'' nipple but have to get used to you/new environment as well, and the longer you wait, and hours do make a difference, the harder it is for both to be accomplished. I personally do not have the patience to start any of them, but thank God my wife does. If you have a stubborn one, spend time with them, hold them til they calm and beyond, lay by them, etc. My wife will take some of those stubborn ones, get on her knees, stand them to their feet and place them between her legs with their butt pressed against her, then corral them with her arms and force the bottle in. Some of them will struggle like the dickens and then ALL of a sudden begin to suck. Often this struggle will have to be repeated, but try in between to put some calm in them. I've also seen some of them for a time take the bottle better/quicker laying down. Best of luck!