Thanks! Not sure how I missed the 1953 mention on the Apollinaris one. I don’t see one on the Parein though. My googling suggests that Parein Merced and ceased to exist in the mid-60s so I would think that was issued before then. And as noted the only mention I found of the Parein card was someone on net54 who very matter-of-factly called it a 1950 issue. But I can’t imagine that cards with such a similar design were all that far apart — maybe a few years at most.
This website seems to suggest Spirou stamps started in 1961, I think?
http://www.toutspirou.fr/