Thomas Otter asks "How long does it take to implement SAP?". He then answers that difficult question himself:
The best answer to this question is with another question.
"How long did it take you to buy it ?"
Organisations that can make procurement decisions quickly, 99 times out of 100 can implement quickly. If you take years to decide whether to buy or not, it is likely that the implementation process will looooooooooong too. The biggest factor in software implementation timing is the organisation’s ability to make decisions and follow through on them.