If you're getting scheduled by Niagara Falls like many of us Ottawa applicants are, I've found they are really quick at sending the certificates (unlike the slowness of Ottawa in the past of waiting months for the certificate!)! We had the oath on Wednesday August 3rd, we replied with the signed form within a couple of minutes of the oath finishing, no urgent request, and they sent out the certificate on August 4th! I wouldn't wait for in person if your desire is to get the certificate as soon as possible. I assume there will be a long wait for in person.