So I called AC today(22 hours before my flight leaves to be exact), and demanded a change, there was no problem at all. They changed my flight to AC810 on May 6th(5 days later than the original date).
I made sure the booking class was ok, and it turned out to be a Flex fare with code H, so I still earn 100%. Some folks thought I was crediting to Aeroplan, but it was actually another program so it was slightly more complicated.
If you are wondering, I didn't pay a cent. Other than the 25 min wait on the phone, everything was ok. And for future reference they told me that incase of a flight time change by Air Canada, if the flight is an international flight there can be free changes up to +/-7 days from the flight date. And for other flights it is +/-3 days.