Jason, who is quoted a few times in my User Adoption Strategies book, has recently commented that user adoption activities should start before go-live. I agree:

“Clients often place priority on the technical build and implementation over end-user readiness.

Their assumption is that once the new system becomes operational
(go-live), they can focus on getting end-users to engage the system as designed.

However, clients often have too little knowledge of end-user needs and barriers which leads directly to inaccurate usage and/or less than full adoption.

For example: a client has not fully defined and educated end-users on process changes required to align with operating new system. End-users will make mistakes in the new system by incorrectly following old process steps.“

Read more: Why User Adoption activities should start before go-live

If you want more than what Jason talks about, check out my book on user adoption. Most of chapter 2 – “The Context for User Adoption Strategies” – tackles this issue and says that you can’t leave user adoption until the end or treat it as an afterthought.