One of my favorite books that I hand out to every BSA I meet is:
https://www.amazon.com/SAP-Project-Management-Implementation-Guide/dp/1592299490
It’s written based on SAP but it’s General and all of the techniques can be applied to any ERP.
If you aren’t doing what the book says and Bryan mentions, you simply aren’t implementing, you are a chicken without a head thinking you are implementing 