I can't answer you in terms of price. But in late November, you will start competing with holiday traffic to and from GUM. A lot of the military families leave GUM for several weeks about that time. It is also a good time for many relatives of military families to go visit for the holidays and weather. For this reason, many of the flights end up being sold out. Now it is only April and you have plenty of time, but if you want to take a popular flight, such as a Saturday HNL-GUM, the earlier you book the better.