This depends on the size, age and model of the refrigerator. It may take several hours to 24 hours for the refrigerator to reach the set temperature. The process can be accelerated by placing non-perishable goods in the refrigerator. The temperature in the refrigerator cannot be measured properly by feeling the air inside. The best way to tell if the refrigerator has reached the set temperature is to place a glass of water in the refrigerator with a thermometer in it.