International arrivals to YVR will go through Canada immigration and customs. The line at the immigration hall can be long in the late morning, due to lots of large aircraft from Asia arriving around that time.
http://www.yvr.ca/-/media/yvr/docume...glish-2017.pdf shows the terminal map and various possible connecting paths. You would follow the path from the international gates (D 48-78) to Canada, which is down to the level 2 customs hall (including picking up checked baggage), then back up to the Canada gates (A, B, and C).