iMac to new MacBook Pro

I didn't see anything recent on this topic. I have a late 2009 iMac and I want to migrate everything to my new MacBook Pro (July 2014). It's a refurb so I think it has Mavericks. My iMac has Yosemite. Do I need to update the new MacBook Pro before I transfer anything? Also what is the easiest way to get an exact copy of my iMac to my MBP? I have time machine backups and I also bought a thunderbolt cable so I have a couple of choices.

Any help would be appreciated. Also how long does the process take? I have appr. 250 gb on my iMac.