It will depend on what temperature you plan on cooking it. I normally cook brisket at 250 to 275. If I was planning on serving it by noon, even at those temperatures, I would start it going no later than 8:00 PM the night before. You can always foil, wrap and towel if it gets done too early. If you do start it for an overnight cook I highly recommend that you use a remote thermometer with an alarm to alert you of the pit temp and the meat temp. The last one I did I used my Maverick ET-732. Next all nighter will be done with the Smoke Thermometer from ThermoWorks.
Even with the Rec Tec I would monitor your pit temp just in case of a "flame out" in the middle of the night.