Due to multiple factors, expect to potentially pay more when booking in April. For low rates, May can be a great choice for travel to Varadero. Flights to Varadero from New York John F Kennedy Intl Airport in May are about $548 on average during May, but can be found for as low as $295.
Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from New York John F Kennedy Intl Airport to Varadero as you normally would.