Not till the latest raw because the author put too much fucking water in it. I'm still considering whether to drop the novel or not.
There is no strict answer. He begins awakening early on, in chapter 16, and has steadily grown as a mystic. Around chapter 500, Spoiler he has a big fight as a mystic as well. But unsurprisingly, he has room to grow. Kingdom's Bloodline is not like your standard xuanhuan, were the MC obtains new powers, masters them and then neglects them for newer powers in an endless cycle. Thales is largely reliant on the same methods we have seen from the beginning. He just becomes much more adept at utilizing them.