My mini seems to cook faster than the temperature reads. It's not uncommon to see temps hovering around 200°F but it seems to cook as if it were closer to 250.
I've run into another problem later in the cook. Ash falls down and tends to block the center bottom vent (Smokey Joe Silver models) I found a can just big enough to cover the holes and cut it just short enough to fit under the charcoal grate. I then made some holes near the top to provide an unobstructed air path.
If you have the Smokey Joe Gold with the vents on the side this should be less of a problem. In fact I just picked up one off CL yesterday but have not had a chance to try it.