In order to prepare roasted chicken, you need to first preheat the oven to 350 degrees F. The time needed to roast a chicken varies with the thickness of the meat. A large chicken could even take about 2 hours to fully get roasted.The general thumb rule for preparing roast chicken is a cooking time of about 20 minutes for every pound of meat and another 10 to 20 minutes at a temperature of 350 degrees F in the oven.n order to prepare roasted chicken, you need to first preheat the oven to 350 degrees F. The time needed to roast a chicken varies with the thickness of the meat. A large chicken could even take about 2 hours to fully get roasted.