Hi there and welcome!
The first thing to address with a brisket and your approach is that it is never done based on time. Briskets are only done based on it's tenderness. It is tender when u can stab it
all over with something like a kabob skewer and there is no resistance.
You use temperature to indicate when to start checking for tenderness, not time. I start checking around an Internal Temp (IT) of 200F. Briskets are hard to get proper temperature thermometer probe placement so I put in 3 and usually 1 is placed well haha. You place the temp probe in the center yet thickest most portion of the FLAT muscle of the brisket.
Now on to time talks. At a steady 275F smoker temp, a brisket 8pounds or heavier will take just over 1hr a pound, non-wrapped, and never opening the smoker door until time to check for tenderness.
I give u this time information for planning purposes.
So at 275F a 12 pound brisket may take about 12-13 hours if u dont wrap and u dont open the door the whole smoke until time to check for tenderness.
When time planning on a brisket or a porkbutt add 4 hours of extra buffer time. So your brisket at a smoker temp of 275F would be started 16 hours before u plan to eat. If it finishes 4 hours early then u are golden and u just double wrap tightly in foil, then wrap tightly in 3 bath towels and set it on the counter and 4 hours later it will be piping hot and ready to slice and serve.
IF the brisket takes longer than 12 hours... well u have 4 hours of buffer time for it to finish so again u are golden!
As for wrap vs unwrapped, I have never done a butcher paper wrap but have done a number of foil wraps. For me the brisket is 10x better if u dont wrap and u just let it go till its done.
I also suggest you trim the thin portion of the flat muscle off and repourpose it cause it will just dry and burn up while the thick part is still cooking, see this image to illustrate what area i mean to cut away. What is left of the flat muscle is then about uniform in thickness and u dont lose that good meat u cut away cause u can throw it in and smoke it and pull it early if u want.
See here for all kinds of brisket triming and cooking tips:
Well I have had a number of private messages where people ask for more info about what I do when I trim away the thin Flat portion of a brisket I smoke. So today I figured I would just post about it with plenty of pics so it becomes easier to understand vs when I just go "blah blah blah trim...
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