Make a Time Machine or Carbon Copy Cloner backup and make a Genius Bar appointment on support.apple.com.
Repairs in my experience typically take 3-5 business days, or sometimes shorter.
If you're in a position to have your Macbook shipped to your home or business, that is an option (worked out great for me) if you specifically ask for it up front rather than going back to an Apple Store to pick up. There may be an AASP that could offer the same service in your area if there's no Apple Store. Rarely these days do repairs get done on portables in the store, but it completely varies by location and traffic from my experience.
You can also request to ship the machine in for repair as well, calling 1-800-APL-CARE or starting a live chat from the above support address.
Hope this helps.
