In general when looking for the cheapest flight to Brasilia, try to book your flight during the month of April for the best deal.
In general, most flyers find the cheapest time to book a flight to Brasilia is about 60 days prior.
From most locations, the cheapest flights to Brasilia are found on a Thursday. Booking a Saturday departure is usually the most expensive.
Generally, when visiting Brasilia, midday flights represent the best value. morning flights are likely to have higher prices.