Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from Delhi to Burlington as you normally would.
Expected rainfall in Delhi is more than in Burlington. You can expect this to be the case over the next 5 days.
You can imagine temperatures to be in the 40 °C range in May. The weather in Burlington is generally colder than Delhi's. As flight availability is subject to become more limited as peak season approaches it is ideal to book in a timely manner.