In general, when looking for the cheapest flight to Natal, try to choose a flight departing in May for the best deal.
In general, most flyers find the cheapest time to book a flight to Natal is about 60 days prior.
From most locations, the cheapest day to fly to Natal is Monday. Most users found that departing on a Sunday was most expensive.
Generally, when visiting Natal, evening flights represent the best value. midday flights are likely to have higher prices.