Try before you buy!
Changing a country's voting system is often very complex and disruptive. Heart and Head was designed from the beginning to minimize the impact on voters, infrastructure, Elections Canada, and Parliament.
Because the changes are so minor, Heart and Head can be implemented quickly and inexpensively. It can also be undone by reverting to FPTP.
The only changes needed to implement Heart and Head are at Elections Canada and in Parliament itself. Both need to implement a change to the vote counting process — Elections Canada for the General Election, and Parliament for votes in the House of Commons.
These changes are so minor they can be easily accomplished within one year of deciding to implement Heart and Head.
Because the changes needed to implement Heart and Head are minor, they are also reversible. The suggested referendum process is:
Run the 2023 election using Heart and Head.
Run the government using Heart and Head for one term.
Run the 2027(?) election using Heart and Head and hold a referendum during that election to decide whether to keep Heart and Head or revert to FPTP.
Using Heart and Head for one parliament allows the citizens (and the MPs) to see it in action. This will greatly reduce misinformation and fear, allowing citizens to make an informed decision on its actual merits.
Citizens get to "try before they buy"!