I have a question for you, my project is to get certified in ISO 20000: 2011 started in May of last year, and I have the document review (phase 1 of the certification) on April 22. However, I know that in September 2018 the new version "2018" came out. Will I have a problem if I am looking for the certification in the 2011 version? What do you think?
No, you don't have problem certifying against 2011 revision of the standard.
I would suggest to continue with certification according to 2011 revision ( I have such project as well) and next year "upgrade" to 2018 revision of the standard.