Alright, so I see this question pop up a lot, and honestly, I think people stress about it way too much. The publisher's official order is fine, but if you really want to dig into the world-building chronologically, it gets messy. 'Kingdom of Ash' obviously starts the whole saga, but reading it first can feel like jumping into the deep end without knowing how to swim.
My advice? Start with 'Tower of Dawn.' Yeah, I know it's technically a mid-series book, but it functions almost like a prequel for several key characters, especially Chaol. It sets up the political landscape and the magic system in a way that's less overwhelming than the main sequence. Then, loop back to 'Kingdom of Ash' and proceed from there.
Some purists will yell at me for this, but I found it way more satisfying. You get the 'why' before the 'what,' which made the bigger conflicts in the later books hit harder for me. Just skip the novellas on your first read-through; they're more for superfans who want extra crumbs.