Yes, September is going to be packed. But when you think about it, where is that “good window” to be found when new major competitors are constantly emerging and the old ones aren’t disappearing from the market either? Tomb Raider moved to February, so that’s not a good time either. At some point, you just have to dare to push the game to market and hope for a long tail 
Puha mentioned on X that “Hands on impressions are coming quite soon”. In games like this, gameplay is really what’s emphasized, and if they nail that, this will turn out well.
Additionally, Puha also mentions “The most important thing is to launch a great polished game. Instead of launching too early, I’m sure we all agree on that. We also took great consideration with the pricing of the game. Trying to ensure we launch in the best possible way.”
You can’t really ask for more than that, though there are certainly many ways to achieve it.