Exceptions are “exceptional” by definition, and always exist no matter how rare. Just because research in organizational change shows a strong correlation between certain factors of success and failure does not make these axiomatic. My most successful clients make themselves the success exception, and you can too.
In my experience, I have never seen any dramatic change of any significance gain widespread cross-organizational enthusiasm before implementation, but have often seen such change succeed nonetheless despite lack of initial buy-in. So I advise that action first, buy-in later works, as long a you do things right. There is no need to delay change to seek buy-in.