how long does the migration process take?
How long does the migration process take? And can you speed it up?
MacBook Pro with Retina display, Mac OS X (10.6.4)
That's rather like asking how long is a piece of string.
It depends on how much you've got to migrate. Make sure that you run software update on the old machine before you start the migration. Failure to do this is one of the biggest causes of problems people have with this process.