RSM Richter, a Canadian accounting firm, addressed software implementation in two recent issues of its midsized companies publication, Advantage. They are short, balanced and well worth reading. In Part 1, they do a good job of setting realistic expectations:
Documenting and automating every minute step of every process in a business cannot be put on a fixed, linear implementation schedule. Unforeseen problems will arise, requiring changes to those business processes and/or the software itself. Sometimes these changes can impact the timeline by weeks or months.