Flights are available daily, but you'll have the best luck finding inventory with midweek departures. Peak summer dates are blacked out. However, you should be able to see wide open availability through May and then again from September onward.
As an example, I found seats departing ATL on Tuesday, April 9 and returning from YVR on Monday, April 15, 2019.
We're seeing lots of great deals departing Atlanta today, so make sure to have a look at our ATL departure page for a full rundown on what's on sale.
Need a place to stay in Vancouver? Here's what's available for the mentioned dates on Hotelwatchdog.