My 07 Avalanche frequently does not start when cranking the first time. (Cold or hot) Once I stop, and try a restart it fires right up. Runs great after it starts.
Since it starts at all, the problem is probably fuel related. Worst case it might be a bad fuel regulator or pump. It may also be a leaky fuel injector, which would flood the engine with gas while the car is off, and after you try to start the car, you would clear the built up gasoline and after a few minutes the car would start and run fine. This is not only cheaper to fix, it is more likely. Bring it in and pay to have the fuel pressure tested and the injectors tested, or buy the book and the tools to do it yourself.