As others said, it takes about 2 months for the paperwork, then you have to set an appt and appear in person for both US and Canadian interviews. I did my interviews at the Seattle Nexus office (BFI), which, in August, did not have Iris scanners, so I ended up having the scan done at YYZ Nexus office this week to complete my process. I used my old Canpass card to enter Canada and my Nexus to depart...... Worked great!
LNK