Right now you have summer prices, familys who want to book next year or who had a bad summer, juts check its not a school holiday your booking to depart at or return and I would say book around October/November. December/January I always say its hit and miss for April time purely you have Christmas and some people buy holidays as a sale and it is factored into pricing. Track the schedule on Google Flights and it will let you know if it goes up or down