Oh, we’ve been metric for most of my life, though I vaguely remember when the big push happened in Canada. It was in the late 70s and iirc was supposed to be a coordinated North America-wide transition, but then the US backed out. Canada largely followed through.

I remember getting fresh new textbooks at school with metric everywhere and all the road signs switching to kph. The weather forecasts switched to Celsius. There was a period there when I related to temperatures around freezing better in C and indoor temperatures in F because our thermostat still read F.

Some units involving cooking measures, building materials, and paper sizes remain non-metric in Canada. This is likely because we still need things to be interoperable with the US. One funny thing I remember though is that even before our switch from gallons to litres, we still had to do a conversion because we used imperial gallons that were slightly larger than the US ones!