Sorry I didn't get in here sooner... I cooked on a Brinkmann Gourmet for about 4 years, pre- WSM. My advice (maybe too late) : fill the water pan with hot water (I usually used one kettle full of boiling water, and a second one full of hot tap water) - no need to burn charcoal just to heat the water. Keep an eye on the fire - especially if you use briquettes. Ashes tend to build up and cut down on the air flow, causing the temperature to drop. You'll no doubt need to refill the water pan about halfway through the cook. I also generally would have to lift off the body, stir the coals to get rid of the accumulated ash, and add more (unlit) charcoal at about the 6 hour mark. I modified my Gourmet with an adjustable damper over the air intake to let me control temperatures, and a grate inside the charcoal pan so ashes would fall through and not smother the coals, and it would hold a steady 225-250 for up to 6 hours.
If the temperature drops and you have to add more charcoal, you can get it up to temp quicker by putting a small stick or something similar between the charcoal pan and the center section, to give some added air until everything is lit.