There is also a direct bus, It leaves Montezuma at about 6:30 am and you have to change it Cobano where it merges with the Sta Tersa bus. Then it leaves Cobano between 7 - 7:30am.
The dirver usually yells out 'aeropuerto' but it does no harm to let him know also when you board.
The directo bus also goes on the ferry and is locked during the trip, so no need to haul your luggage into the ferr, but hang on to all your bus & luggage tickets. You need the bus ticket to reboard after the ferry, and your luggage tickets to reclaim it. Thankfully they are scrupulous about checking luggage tickets