We do not have enough data on this route to provide a reliable graph showing how many days before departure it is the best to book.
However, usually the closer it is to the departure, the more expensive the tickets are.
The most popular airlines on the route Toronto - Curitiba: Air Canada (AC), American Airlines (AA), Delta Air Lines (DL).
The cheapest flights you can book on the route Lester B. Pearson (YYZ) - Afonso Pena (CWB).
There is no direct flight on the route desde Toronto a Curitiba
The shortest flights with change last about 13h 30min.