Prepare and mix the stuffing ingredients immediately before you plan to cook the chicken for best results. If you wish to complete some preparation work ahead of time, mix all of the dry ingredients together, and mix the wet ingredients together separately, but do not combine the dry and the wet ingredients until immediately before you stuff the chicken and cook it.

To safely perform some of the preparation work ahead of time, cut up the bread and mix it with the onions, celery, and any other vegetables you're using, plus spices. Do not put eggs or other wet ingredients in, but stir them together in a separate bowl. Prepare the chicken by removing the giblets and neck, rinsing out the cavities, and patting the chicken dry with paper towels. Refrigerate the prepared stuffing ingredients and the chicken overnight. When you're ready to start cooking, combine the stuffing ingredients, spoon them loosely into the chicken cavity, and roast the chicken immediately after stuffing.

If you mix a complete stuffing using both the dry and wet ingredients, but then aren't ready to stuff and cook the chicken yet, the only safe storage method is to freeze the stuffing, according to the Food Safety Inspection Service of the U.S. Department of Agriculture. Spread the prepared stuffing in a shallow storage container, cover it, and freeze it immediately. The USDA recommends cooking the stuffing without thawing it. Remove the frozen stuffing from the freezer, break it apart into small chunks, and place it into the chicken cavity. Put it into a preheated oven right away.

Whichever method you use, roast the stuffed chicken according to your recipe. When both the stuffing inside the chicken and the chicken meat at the thickest part reach a temperature of 165 F, remove the chicken from the oven. Allow it to stand for about 20 minutes and then transfer the stuffing to a serving bowl. Carve the chicken and serve it immediately.