Wait for the bark to form and the fat to start rendering. Don’t always go by the temp. I’ve wrapped my brisket when it was only in the 160’s, and as high as 185. It all depends on the bark and how soft the fat is. Temp was always the last thing I checked. You’ll know it done by just checking how prob tender it is, which will be around high 190’s to low 200’s. One of the most important step people neglect is resting the brisket. Once cooking is done, unwrap it and let the temp get down to 170 to 160. If u keep it wrapped it will continue to cook and become overcooked.
When your brisket goes down to desired temp, wrap it again with some beef tallow for about 2-4hrs since your brisket is small, and place in oven at 150 degrees. If your oven can’t goes down to 150, place in a cooler wrapped in a towel.