Because the Zhongli banner just re-ran, along with the Venti re-run banner in March-April, you probably won’t be able to get them unless Mihoyo decides to re-run it again (which I think is unlikely). If they do, it’ll probably be a really long time from now, because there are lots of new characters to be released. Ganyu is rumored to rerun sometime around the 2.0 update I think, before the Xiao re-run banner. I’m pretty sure Klee is also going to be re-run sometime in the 1.6 update starting June 9th. All the other 5 star exclusive characters will probably going to be re-run in order from oldest to newest sometime in the future.
Hope this helps.