Time is subjective when it comes to safely cooking turkey or any poultry as different variables can cause the meat to cook at different speeds. This is why I always recommend using a thermometer to check the food's doneness. Either a simple instant-read thermometer or a leave-in digital probe thermometer will allow you to monitor the food's temperature. Turkey breast should be cooked to a minimum of 165F internally. If you need to budget how much time the cook should take, a safe bet is for the meat to take about 15-20 minutes per pound when fully defrosted.