Freo, to answer your question, and not argue with anyone else's view on this matter - I never use the park brake from "off blocks" until completion of the flight.
If you roll to the runway without a problem, the brakes are off! The take off run is not the time to find out that they might not be.
I am aware of two accidents in Australia, one of them fatal and both total hull losses, due to take off when the park brakes were not fully released. On the non fatal one, a Metro, the brake was set on the runway prior to take off.