That depends. First, if it's a baby why does it weigh 5 pounds?
Smoker temperature has a huge effect on smoking time. With a 5 pound chicken, smoked at 225 degrees you're looking at 4 to 6 hours. If you can get the temperature of your smoker up to 300 degrees, you'll drop that down to 2 hours or less.
If you brine your chicken, it will take less time to smoke, too. And if you split it into two halves, also shorter time.
