Just a quick win blog to mention and give a heads-up that when you are in the process of configuring vIDM and o365 you might encounter native clients prompting for authentication and a big ass delay when you flip over the authentication and the requested domain from managed to federated with vIDM. This might be up to eight hours!!! Thanks to the #community #vExpert that I got this answer quite fast because I recalled that Laurens van Duijn put something similar in the vExpert Slack group mentioning that he saw this kind of behavior.
So in summary, do it on a Friday and inform your users.
Big shout out to Laurens van Duijn and be sure to follow him on twitter and his blog