If you have an older Macbook Pro, such as say a 2011 one, even if it has a thunderbolt cable port on it, it will be Thunderbolt 1 standard and will not handshake with a newer MacBook Pro on the Thunderbolt 2 standard. So all these machinations noted above will matter not.
Test it for yourself - hook up the new Mac to a newer Mac both on Thunderbolt 2 and the Migration Assistant handshaking will work right away, including if you start on WiFi and then hook up the cable afterwards - will be instantly recognized.
If you are trying to migrate from an older MacBook pro to a newer one, the best you may hope for is ethernet. Since the newest MacBook Pros do not have ethernet ports, one solution that worked for me is to connect the ethernet cable to the old Macbook Pro, and then connect that ethernet to the thunderbolt port on the new MacBook Pro via an ethernet to thunderbolt adapter, such as the Apple Thunderbolt to Gigabit Ethernet Adapter MD463LL/A.
Another solution is to do a time machine backup of the older Mac, and then do the migration from that backup. This is also quite a bit faster than simply transferring the data from the old MacBook Pro itself, straight across WiFi.
Transferring say 500 Gb of data from the older Mac to the newer Mac via WiFi alone, will take 3 - 5 days, and may be unreliable besides since packets of information may be missed. Via ethernet will take about 8 hours (Thunderbolt just a couple of hours, but as noted above, not an option).
So don't your waste your time with all of the above "tricks" people have written about if you have a Thunderbolt 1 machine - it will not handshake with a Thunderbolt 2 machine directly. | 
