To quote one of my favorite bbq'ers Harry Soo, that's a 3 hour debate. Lol. That being said, it may yield better results to separate the point from the flat since it's your first cook. The reason I say this is because the point and the flat are often "done" at different times. If they are separate, you can monitor each section individually and pull each of them when they need to be pulled. Another thing is that they will be done much quicker if they are separated.
There's really no right or wrong answer here. I separated in this instance because of time constraints. When I cook in my back yard I usually just leave the brisket whole.
Pros to separation:
Quicker cook
More seasoning/bark on the outside of the meat
Can monitor each section individually to check for doneness
Cons to separation:
More time spent trimming