Question : Is price more important than specific travel days for you?
Answer : For the month of December, the cheapest day to fly is Monday. Having flexibility in your travel plans means you can save, so be sure to plan ahead when possible.
Question : How often are prices changing for this route?
Answer : Flight prices for YUL to KBP change much more than the majority of routes. The further out you book a route, the more likely you are to save.