First time brisket..
Don't worry bout the IT. Usually around 190 I start checking a few different spots on the flat. You want to stick your thermometer in every 30-60 minutes until it feels like you're sticking it in a warm butter. If you pull it before this the flat will more than likely be tough. Don't sweat the point now. It has enough fat to keep it good until the flat is ready. Don't pull til it probes right!
WSM 22 ~ WSM 18 ~ Maverick ET-732 ~ Flaming Fast Thermapen ~ Weber SS Performer ~ Weber 22 OTS ~ Weber 22 OTS ~ Weber 22 OTPlus ~ Weber 22 OTS ~ Weber Q300
When all else fails just ask yourself, WWGALD???