Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from Portland, Maine to Abaco Islands as you normally would.
Due to multiple factors, expect to potentially pay more when booking in December. For low rates, October can be a great choice for travel to Abaco Islands. Flights to Abaco Islands from Portland, Maine in October are about $661 on average during October, but can be found for as low as $478.