For all of you people who are wondering when Xiao is going to be released, its not anytime soon. So calm down. The next banner is going to be most likely Zhongli's rate up banner, I have an entire post on the next banner.
Anyways back to the main topic, Xiao is expected to be released in v1.3 and we're not yet even at 1.1 so expect him to be released in around March or April 2021. Who knows, maybe he will get released earlier or later. But for now, you don't have to worry about trying to pull XIAO. His banner will not come out anytime soon.