Completing my ticketing after midnight UTC and it's showing some janky dates...
Cowtool:

Email Receipt

Air Canada Website

Fingers crossed this isnt going to become an issue...I got the dates confused because I happened to fly across the date line yesterday evening/morning (?) so hoping my math is correct. Thought the promo ended ~18 hours ago (at the time of this post it's past 1800 PST). Fingers crossed on whether AC IT will credit me correctly...
Booked YVR-YEG-YYZ-YHZ-YYT-YYZ-YVR via ITAmatrix, took a good while to hunt down a fare that actually would go to seat select. You would think it would book as a St John's round trip but no, apparently I'm heading to Halifax....6910 SQM for a good transcon segment run in economy (it's for the miles).