This would vary WILDLY unfortunately. Wouldn't even stray into "rough" without knowing a lot more for example
Number of subsidiaries
How technical the client is
Capacity of technical users at the client (someone who's really good but too busy to help doesn't help)
Is it inventory?
Is it project based?
Multiple currencies?
is this just a business split?
Acquiring a business?
Moving something to oneworld that should have been from the start? (hint - this gets stupid expensive quick to unravel)