In general, when looking for the cheapest flight to Sofia, try to choose a flight departing in February for the best deal.
On average, from most locations, when planning your trip to Sofia, try to book your flight in the region of 60 days in advance for the cheapest prices.
From most locations, the cheapest day to fly to Sofia is Thursday. Most users found that departing on a Saturday was most expensive.
On average you can find the best deals on plane tickets to Sofia when looking for flights with evening departure times.