Oceanjet opens bookings about a month ahead, so October should be available. They run several departures daily, first from Cebu around 5-6am and the first return from Bohol near 6-7am. Arrive an hour early. Given your 20kg luggage, Business Class is worth it since standard only includes 10kg. For updates on prices and conditions, I've been relying on ferries in the Philippines for accurate schedules and baggage rules. Fuel costs and visitor numbers shift often, so check closer to your trip.