My pit bull keeps attacking my labrador what can I do?

Both dogs are male. I have an appointment with a dog behaviorist already, but that won't be for another 2 weeks. I need some advice in the meantime. The pit bull is 9 months old, unneutered. (I have an appointment to get this taken care of also) the labrador is 3 yrs old, and neutered. They get into fights if someone comes over. and occasionally fight over treats, but not at mealtime. The pit was raised around the lab since he was 8weeks old, and this just started. Tips or tricks to keep this from happening would be very much appreciated. Both the pit's parents were dog friendly, so I do not think it's a breeding issue, just a breed issue.