It’s unlikely, because putting the month first is a US thing. In France it would be 20/04, or “20 avril”.

Still, stoner-cultures in many countries in Europe celebrate 4-20, definitively a bunch of Frenchies getting extra stoned that day. It's probably the de-facto "international cannabis day" in most places in the world, at least the ones influenced by US culture which reached pretty far in its heyday.