When preparing confit, do you start ingredients in cold fat, or do you add it when it reaches cooking temperature?

My rule of thumb is to use room temperature vegetable oil.

I add a lot of vegetables (onion and garlic mainly) and herbs in the bottom of the pot and the meat goes on top of it; this way, when the oil is heated and the water start to leave the food, it will remain in the bottom and the meat will still be in contact with the oil.

Traditional duck confit is made with duck fat, which would be a solid when cold. That will not work so well. So, the cured duck is placed in a crock, and warm duck fat is added to cover. This is then placed in the oven at a low temperature. After the cooking, the duck is left submerged to cool, and be stored in the fat. There is no splatter risk, because the temperature is not hot enough, but the duck is generally blotted, before submerging in fat, to remove excess moisture and herbs or spices that were used in the cure step.