http://trafficticketsolutions.ca/stop-sign.php
From the MPI Drivers Handbook page 26.
https://www.mpi.mb.ca/en/PDFs/CompleteHandbook.pdf
'Stop signs
At a stop sign, you must come to a complete stop at the appropriate
places illustrated below. Before proceeding from a stopped position,
you must check and yield the right-of-way to pedestrians wanting to
cross the street. When pedestrians are clear, you may then slowly move
forward for a better view of traffic and, when safe to do so, you may
then proceed to turn or cross the street. '
There's no mention of any 3 seconds.