Hi, Just want to share my recent experience for NEXUS application for not being a Canadian PR more than 3 years. I used to live in the U.S. in F-1 status for more than 6 years and I became a Canadian PR in January 2018. Before I became a Canadian PR, I also lived in Canada holding open work permit for less than 1 year. I applied for NEXUS in early July 2018 and got conditionally approved in late August. So I believe the 3 years residency requirement does not necessarily apply to the time after becoming a Canadian PR. In my case, obviously it counted my U.S. residency.