As an eager overthinker I like your reasoning. My typical arrival date in Europe is the last week of August with a start date of the last Tuesday or Wednesday in August. My overthinking reasoning is that I avoid the last weekend of locals returning to the city as well as the hump of walkers who start on the weekend.
Eventually overeager members of the September wave will catch up to me and I’ll be carried along effortlessly on its rising crest, several days wiser then the newly arrived Septembertistes. They will be tired in spirit and body having walked too quickly and I’ll be fit and smug. I’ll be able to say vexing things like “isn’t this a lark?”.
But of course such behavior is not the Camino way so I’ll have to buy them a round of drinks in contrition.
This is based on absolutely no facts, charts, bar graphs or statistics, nor tide tables or moon phases.