How will the baking time/temperature change if I only have access to an cast iron skillet right now? Thanks.

A thermometer is always your friend in the kitchen. In fact its indispensable. Most breads are cooked through with an internal temperature between 190-200 degrees. Over the years I've experimented with different quick breads, yeast breads, cupcakes, etc. Its a fool-proof methodology.

your answer has to do with how thick/high the bread can be, given your pan. if the recipe calls for a loaf pan, and your skillet is actually a skillet and not a loaf pan, so it is maybe 2-3" high, then your bread will bake faster in the skillet because it is not as high and the heat doesn't ake as long to bake the center. so start checking for doneness, using a toothpick inserted into the center, maybe halfway through the loaf pan baking time, and every 5-8 minutes after that, until the toothpick comes out clean (no batter clinging.)