Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from Calgary to Saint Petersburg as you normally would.
Finnair is one of the carriers that may have flexible change policies. You can use our site to filter for other airlines that may also have this kind of flexibility.
This flight path from Calgary to Saint Petersburg Pulkovo was viewed by 14 users in the past month. Keep an eye out for changes in search interest prior to high and low season.