I learned the hard way the when you file a VFR flight plan (required) and put down a departure time, they assume you departed at that time. You do not have to "open" a VFR flight plan like we do here. If you don't show up at your destination airport at your ETA plus a couple of hours, they start SAR. In other words, if you file a VFR flight plan and things change, notify their FSS folks.
THIS is a very important difference between Canada and the US.
Here in Canada we have lots of uninhabited areas, lots of open space, lots of places for an airplane to go down and never be found. It's all too common for a crash scene to be discovered years after the occurrence date.
With this in mind, in Canada, a VFR flight plan is a VITAL SAR tool. In the US it seems more of a "nice to have" - up here, it's often what makes the difference between being found and starving/freezing to death. When filing, and when flying, always keep this tidbit of info in mind.
Also, if you are overdue by as little as 30 minutes, Flight Service will start a communications search for you. They will call your cell phone number that you filed in the flight plan. They will call your airport of destination to see if you've arrived and just forgot to call FSS to close the flight plan. Then they'll call your alternate contacts to see if they know where you are. Believe me, your wife and kids don't want to receive this call.
The best example of this I've seen so far was on a fairly local flight of 130nm. Winds aloft were forecast to be less than 8 knots, while actual winds were closer to 35 knots. I arrived at destination 15 minutes late. As I was taxiing in the local FBO told me over the radio that FSS was looking for me and that I had better call them. I was only 15 minutes late and they were already looking for me. THAT's how seriously flight plans are taken here.
As an adjunct to the anecdote above, be aware that Canada is big. Flying along with flight following, you will frequently hear the Terminal controller say "Radar services terminated"... you've fallen off the edge of their radar. If you want to know the "next" radio frequency to use to contact the next controller, look up an airport near your route of travel and a few miles ahead of you. In the "COMM" section of the Canada Flight Supplement listing for that airport you will see a frequency listed there - sometimes shown as PAL, or TERM or DEP as well as the name of the controlling unit, like "Toronto Ctr" or Montreal Term". Dial up that frequency and see if you can raise them to establish flight following as you continue your journey.