QUICK QUESTION-About to set up new computer...

Thanks in advance. I have an old 17" Macbook Pro and just got a new Macbook Pro Retina. I have each of them side by side ready to send all of my data from the old computer to the new computer, but I have not turned on the new computer yet. I don't want to screw up my iCloud ecosystem. So, my question is: In order to avoid any icloud issues, should I log out of iCloud and turn wifi off on my old computer before I start the migration assistant? Then, when it is done, I plan on logging into iCloud on the new computer and erase the old computer....I am hoping this will be a seamless transition as much as it can be.

Any input you can give me before I do this would be great. Thanks!