First brisket questions

Dawgnut

Okay, 7.5 lbs. from Costco sitting in the frig for Sunday, already rubbed. I  want to serve for 6 PM, the brisket goes on when? 6 AM, to be safe? Don't want to be much later than that, I have to be at work at 10 PM

Paul

JohnInCarolina

I’m assuming it’s just a flat. Much depends on what temp you’re planning to smoke it at, but I’d expect under 12 hrs for sure.  Probably 9 at most.  But if you get stuck in a long stall, you can always wrap it in foil and bump the temp up to push it through.  

lousubcap

Welcome aboard and enjoy the journey.  Above all, have fun.  
As above, and if a Costco flat you likely spent more $$ /lb then if you had grabbed a packer (not knowing your general location- you may not have had the option) which lends itself to an easier cook to nail.
Regardless here is a well reviewed flat cook;
https://biggreenegg.com/recipes/brisket-flat/  And if you have a packer then the search function here will likely give you more info than you can inhale.
BTW- just aim to get inside a decent FTC window when you cross the finish-line.  That window is easily 2-6 hours wide and aiming early eliminates a lot of self-generated finish-line stress.
The finish-line, the thick part of the flat probes like buttah.  Don't short change the criteria.  And once you hit it, give the protein at least a good 20 minute cooling rack rest, nekked (if prior wrapped) and then FTC for the duration.  FWIW-