I find it easiest to prep ahead to the point where the meat is cooked and the spice packet added. I don't add the beans and tomatoes because it is hard to have enough refrigerator space to safely store a crockpot, large stock pot, or electric roasting pan full of chili. However, if you have enough space by all means prepare it fully and refrigerate. If you are using a slow cooker insert it is best to remove it from the refrigerator 30 minutes before turning on the heat of the slow cooker. Allow it to sit on the counter and warm slightly. That way the slow cooker insert won’t break.