Thanks very much @crackaddict! I'm now also booked for Thursday at 830AM. There are free options available in many pharmacies for those travelling to Canada but I couldn't find any convenient availability. Check out the following link for some background: https://flytrippers.com/getting-covid-19-test-usa-for-canadians/
Proof of vaccination is required for non-Americans to travel to USA by road/ferry (as well as air). Downloading requisite doc was easy, once I found what was needed! (For those from BC, the health gateway App provides a PDF with QR code for travel purposes).
See you soon!