Due to multiple factors, expect to potentially pay more when booking in May. For low rates, July can be a great choice for travel to Bratislava. Flights to Bratislava from New York John F Kennedy Intl Airport in July are about $691 on average during July, but can be found for as low as $548.
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 Bratislava as you normally would.