The fastest way is to follow the crowds
If you are talking about getting there in the morning (which I assume you are since you mention FP which will be gone in an hour or less after the park opens for the next few months) when the park opens, you will have to walk with the cast members that will be at the front of the park. They will hold a rope and walk you past the FP area and into Carsland. You CANNOT get around them. They will most likely take the path from the main entrance, past the
Carthy Circle restaurant on the right hand side and walk back toward Carsland passing the bugs life area on your left. Going to the other two entry points will take longer.