Since you are in Montreal, Canada, where it its still cold (below freezing on some days), I personally don't see a problem with 0.40% IDY. In fact, if the only change is to use less yeast, I think you can end up with a dough that is not quite ready after 48 hours.
First, let me say that in my opinion 40 minutes is too long for an autolyse rest period. Professor Calvel, the "father" of autolyse, used to use about 13-30 minutes. But that was for around 75 pounds of dough. See, for example, Reply 15 at http://www.pizzamaking.com/forum/index.php/topic,3220.msg74624/topicseen.html#msg74624
. Second, it perhaps useful to keep in mind that autolyse is a creature of the bread world. In that world, the way that dough is proofed to make bread is different than the way that dough is managed to make pizza. In my opinion, if autolyse is to be used, I would limit the duration of the autolyse to about 10-15 minutes. Evelyne Sloman, who wrote a book about pizza making, goes even shorter. For a home setting, she recommends an autolyse of five minutes.
Third, whenever you add IDY late in the dough making process, that will slow down the rate of fermentation. In fact, that is the way that a major pizza chain in the U.S. does it in order for the dough (cold fermented) to last from 5-8 days in its stores. I estimate the amount of yeast to be equivalent to about 0.16% IDY. To achieve that goal, the dough is kept cold, but not frozen, for its trip from the commissaries to the stores, where the dough is also kept cold until ready to use.
Fourth, with a 40 minute autolyse, you are getting good hydration of the dough, with the proteolytic enzymes also softening the dough (there are also no meaningful amounts of acids, if any, to adversely affect the dough). However, with an initial mix/knead of 4 minutes (pre-autolyse) and a later knead at speed 2 for 6 minutes (post-autolyse), the total of ten minutes may be too much for a dough batch weight of only 620 grams (a bit less than 22 ounces).
For a future effort, you might want to lower the duration of the autolyse to about 10 minutes and shorten the total mix/knead time by a few minutes (or you can try using speed 1). For now, I would stick with the 0.40% IDY so that we can see if the yeast quantity was a factor in the results you got.