As per all the questions about when the sports book will be done, we are in development on it now, and expecting it to launch in September - well before the launch of NFL. We build everything in house and do not white label anything so sometimes it takes a bit longer than our competitors but we tend to end up with a better, and more polished product for the extra time.
This is the right approach. I have so many sites just rush and add unoptimised sportsbook sections just to stay in the competition which is an inefficient strategy in the long term. Optimization is key when it comes to this sort of stuff.
Take your time testing and optimising it thoroughly and offer some great promotions to draw in gamblers from everywhere.