Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from Chhatrapati Shivaji Intl to Sarajevo as you normally would.
When travelling, we recommend packing in preparation to handle common weather conditions. The rainfall in Mumbai is typically less than Sarajevo. We can gather that this will continue over the next 0 days.
Expect the weather to be around 34 °C on average in May. As the temperature peaks, try to get your plans done early, as flight price and availability will have an impact on your travels. The climate in Sarajevo is generally colder than in Mumbai.