Although the OP's flight appears to be an early one, I thought I'd throw in some empirical data from a Thursday late afternoon flight out of YVR to LAS this past October for anyone else coming across this thread.
We arrived at YVR just over an hour before departure. No issues with luggage drop off. However, security check line was long (backed to the "door") with only a few lanes going and US customs/immigration was long also. One buddy and I breezed relatively quickly through using Nexus. Other buddy didn't not have Nexus. But he did catch up with us at the Canucks bar just before boarding began.
Also saw one family that politely asked folks in the US customs/immigration line to cut in front so they could make their flight. Some folks told them to cut into the Nexus line (which I wouldn't have cared) but they were concerned that they shouldn't.