In our books, our standard size for a loaf-bread is 1 pound (450 grams), or a piece of dough about the size of a grapefruit. Why did we opt for these relatively small loaves? Because for beginners, they reliably brown without burning, and are easy to bake through to a nice result in the center of the loaf.
Larger loaves need more baking to avoid a gummy result in the center, and that means longer baking times at the listed temperature. Two pound loaves need about 45-50 minutes, and three pound loaves need about an hour. Let the crust get nice and dark. When baking large loaves, temperature is critical, so you must check your oven temp with an oven thermometer (click to see one on Amazon).
More in The New Artisan Bread in Five Minutes a Day, and our other books.