If you become a regular at Hawaii and get to know the manager, Ruby, I find the appointments seem to be honored. The key is to get Ruby's number, which only happens when you go regularly enough, so she recognizes you. Once she know you and you text her for a certain girl, at least one hour in advance, I find there is little to no wait time. She manages both Hawaii and Queen, so the appointments seem to be honored at both establishments by Ruby.