No need to pay to notarize the invitation letter. No point in including a notarized letter saying parent will follow the immigration rules and not overstay. It is not rngircesble and just a waste of money. Only buy one year of supervisa insurance at time. Most insurance companies will only sell you one year at a time because they want to review and claims before issueing another year of supervisa insurance. Do not buy a ticket. It isn’t necessary and actually discouraged. Proof of itinerary is fine. Nobody expects a parent on a supervisa to know their departure date so far in advance. You have to declare family in Canada.