I think alot of attacks happen by the 2nd generation. Our law enforcement has been pretty good about stopping attacks before they happen too. There was an incident not long ago where a guy was stopped before he headed to his destination in southern ontario and that taxi driver was wounded.
https://www.thestar.com/news/canada/2016/08/11/rcmp-fbi-combine-to-stop-terror-attack-in-ontario.html