Prepping a 20 Pound Brisket for Christmas Dinner - advice needed please

[Daba's BBQ]

I'll be smoking a 20 pound brisket for Christmas Day dinner. I won't be back home on Christmas Eve until very late, but want to prep the brisket before leaving for the night.

Is it okay to season the brisket and leave it in the refrigerator overnight until place it on the smoker later that night or early the next morning?

Also, given the size, if I want to serve the brisket at 7 pm, when would I place it in the smoker, at what temp?

I've cooked several briskets before, but always in warmer temps. I live in NYC. And always without much pressure. The last thing I want to do is screw up Xmas dinner for 20 people. Hence, the reason for this particular post.

 

[Daba's BBQ]

I just took it off the smoker after wrapping and cooking for an additional 2 1/2 hours. Total cook time was 15 hours. I'll not let it rest in my cooler for about 3-4 hours.

Pics to follow a little later.

It came out amazing. It was probably the best brisket I ever made. Here is a look at the final product

 

[CMTiger]

This is a success in my book. Pleased with my first brisket

 

[patstock11]

thats awesome , looks really good....rendered that point fat nicely, nice yellow tint..