For landing there will be 2 options for you.
1. You can directly go to Rainbow bridge(Niagara Falls) or Peace bridge(Fort Erie 30 kms away from Niagara) only on
Tue, Wed and
Thursday's after you got your passports back.
2. Call to cic customer care wait for 45 mins on hold
and ask an agent to book an appointment at your nearest CIC office. I believe it could take 4 weeks time to get an appointment. Call cic only after you get your passports back or atleast return tracker activated for your passports, do not call them before.
I would suggest you to go to the border directly. You will finish everything in 30 mins max.