I was in this situation earlier this summer on Maui. In general they were charging folks $50 to jump on the earlier flight. We talked our way on an earlier flight because our flight was late. There was still enough time to connect, but we asked them to do us a favor because we had hoped to eat dinner in Honolulu during our layover and the original (late) flight wouldn't have left enough time for dinner. The Kona Brewing company is an OK place to have dinner prior to boarding a red eye back to the mainland.