H1B stamping for Canadian husband and H4 stamping for Bangladeshi wife

[diner]

Please suggest me for the following situation.

I took the schedule for my H1B and my wife's H4 stamping in London consulate. The interview is scheduled next week. However, I just found that H1B stamping is NOT required for Canadian citizens, they are simply issued an I-94 from the POE. 

In my H1B approval notice, it is mentioned that the country of birth is Bangladesh (I don't use Bangladeshi passport from 2014 since I became a Canadian citizen) and also mentions Consulate/POE is London. Does it mean I must be interviewed at London consulate even though I am a Canadian citizen ? 

Note that, my wife is a Bangladeshi citizen, so she will need to go to the embassy for interview and get H4 stamped on her passport. So should I cancel my appointment (we scheduled together) and just keep her appointment ? If that is the case, then can she get an H4 visa using my H1B approval notice even before I get my I-94 at the POE (so that we can enter USA together)?  

I am confused now, please suggest me the plan of action.

[nr2006]

You are correct about Canadian citizens not requiring a visa to enter the US

They might ask her to attend in Bangladesh (her citizenship/passport country) , if she doesn't have  a resident status in UK.  How did you apply for Interview at London?

Good luck!

[diner]

we got our visa h1 and h4 both from london. As long as you are legally living in UK with a valid visa (she is on her spouse visa via my work visa) it is fine to apply for stamping in UK